A plant planting device, comprising: at least one plant growing tank, the at least one plant growing tank including: a tank body; a tilt member, obliquely provided at a bottom of the tank body, configured to support a plant; at least one flow guiding element, provided on the tilt member; wherein, the at least one flow guiding element is arranged to guide liquid for growing the plant to flow from an end to an other end of the tilt member, the end and the other end of the tilt member being relatively tilted with each other, wherein, the plant growing tank includes a partition board, the partition board divides the plant growing tank into a plant growing region and a liquid buffer region; the partition board is provided thereon with at least one first opening, the first opening is configured to connect the plant growing region with the liquid buffer region; and the tilt member is provided in the plant growing region, wherein, the tilt member is plate-shaped, and the flow guiding element is a plurality of strip-shaped protrusions arranged on the plate-shaped tilt member, wherein, the liquid supply tank is connected with the liquid buffer region through the at least one second opening, wherein, the plant planting device further comprises a lighting device provided above the plant growing tank; wherein, the plant planting device further comprises a frame body, wherein, the frame body includes a plurality of plant planting layers, and the at least one plant growing tank is provided in the plant planting layer, wherein, the plant planting device further comprises a carbon dioxide replenishing device, the carbon dioxide replenishing device including: a carbon dioxide detecting unit, for detecting a carbon dioxide concentration in the plant planting device; and a carbon dioxide supply unit, for releasing carbon dioxide to the plant planting device, characterized in that the plant growing tank further includes a plant fixing layer, wherein the plant fixing layer is provided above the flow guiding element, and the plant fixing layer includes a plurality of plant fixing holes and further includes a flashboard that cooperates with the at least one first opening, wherein the flashboard is configured to adjust an opening size of the first opening, wherein a shape of the flashboard is identical with a shape of the first opening, a size of the flashboard is smaller than a size of the first opening, and the flashboard is pluggable into the first opening. a tank body; a tilt member, obliquely provided at a bottom of the tank body, configured to support a plant; at least one flow guiding element, provided on the tilt member; wherein, the at least one flow guiding element is arranged to guide liquid for growing the plant to flow from an end to an other end of the tilt member, the end and the other end of the tilt member being relatively tilted with each other, wherein, the plant growing tank includes a partition board, the partition board divides the plant growing tank into a plant growing region and a liquid buffer region; the partition board is provided thereon with at least one first opening, the first opening is configured to connect the plant growing region with the liquid buffer region; and the tilt member is provided in the plant growing region, wherein, the tilt member is plate-shaped, and the flow guiding element is a plurality of strip-shaped protrusions arranged on the plate-shaped tilt member, wherein, the liquid supply tank is connected with the liquid buffer region through the at least one second opening, wherein, the plant planting device further comprises a lighting device provided above the plant growing tank; wherein, the plant planting device further comprises a frame body, wherein, the frame body includes a plurality of plant planting layers, and the at least one plant growing tank is provided in the plant planting layer, wherein, the plant planting device further comprises a carbon dioxide replenishing device, the carbon dioxide replenishing device including: a carbon dioxide detecting unit, for detecting a carbon dioxide concentration in the plant planting device; and a carbon dioxide supply unit, for releasing carbon dioxide to the plant planting device, characterized in that the plant growing tank further includes a plant fixing layer, wherein the plant fixing layer is provided above the flow guiding element, and the plant fixing layer includes a plurality of plant fixing holes and further includes a flashboard that cooperates with the at least one first opening, wherein the flashboard is configured to adjust an opening size of the first opening, wherein a shape of the flashboard is identical with a shape of the first opening, a size of the flashboard is smaller than a size of the first opening, and the flashboard is pluggable into the first opening. a carbon dioxide detecting unit, for detecting a carbon dioxide concentration in the plant planting device; and a carbon dioxide supply unit, for releasing carbon dioxide to the plant planting device, characterized in that the plant growing tank further includes a plant fixing layer, wherein the plant fixing layer is provided above the flow guiding element, and the plant fixing layer includes a plurality of plant fixing holes and further includes a flashboard that cooperates with the at least one first opening, wherein the flashboard is configured to adjust an opening size of the first opening, wherein a shape of the flashboard is identical with a shape of the first opening, a size of the flashboard is smaller than a size of the first opening, and the flashboard is pluggable into the first opening.