A microchannel flat tube comprising: a flat tube body comprising a first plane , a second plane , a first side surface and a second side surface , the first plane and the second plane being disposed on opposite sides of the flat tube body along a thickness direction (H), the first side surface and the second side surface being disposed on opposite sides of the flat tube body along a width direction (W), the first side surface connecting the first plane and the second plane, the second side surface connecting the first plane and the second plane; and a row of channels disposed in the flat tube body along the width direction, the row of channels extending through the flat tube body along a length direction (L), each channel comprising a first width in the width direction and a first height in the thickness direction, the row of channels at least comprising a first channel , a second channel and a third channel disposed along the width direction; wherein the first channel, the second channel and the third channel have the same first height, and the first channel, the second channel and the third channel have first widths which are decreased at a fixed rate and meet a linear function; characterized in that the row of channels comprises a group of first channels, a group of second channels, and a group of third channels, the group of first channels comprises a plurality of the first channels, the group of second channels comprises a plurality of the second channels, and the group of third channels comprises a plurality of the third channels, and in that the number of the first channels in the group is equal to the number of the second channels in the group; and the number of the first channels in the group is equal to the number of the third channels in the group. a flat tube body comprising a first plane , a second plane , a first side surface and a second side surface , the first plane and the second plane being disposed on opposite sides of the flat tube body along a thickness direction (H), the first side surface and the second side surface being disposed on opposite sides of the flat tube body along a width direction (W), the first side surface connecting the first plane and the second plane, the second side surface connecting the first plane and the second plane; and a row of channels disposed in the flat tube body along the width direction, the row of channels extending through the flat tube body along a length direction (L), each channel comprising a first width in the width direction and a first height in the thickness direction, the row of channels at least comprising a first channel , a second channel and a third channel disposed along the width direction; wherein the first channel, the second channel and the third channel have the same first height, and the first channel, the second channel and the third channel have first widths which are decreased at a fixed rate and meet a linear function; characterized in that the row of channels comprises a group of first channels, a group of second channels, and a group of third channels, the group of first channels comprises a plurality of the first channels, the group of second channels comprises a plurality of the second channels, and the group of third channels comprises a plurality of the third channels, and in that the number of the first channels in the group is equal to the number of the second channels in the group; and the number of the first channels in the group is equal to the number of the third channels in the group. <EOS>