A locking device, comprising: a quick release coupling board; and a sliding assembly configured to be slidably connected with the quick release coupling board; wherein the locking device further comprises a locking assembly, and the locking assembly is connected to the sliding assembly and is configured to lock the quick release coupling board to the sliding assembly, wherein the quick release coupling board comprises: a bottom plate and two opposite side walls, the two side walls each define a sliding slot, each sliding slot comprises a blocking sheet opposite to the bottom plate; wherein the sliding assembly comprises: a guiding piece and a seat, a shape and size of the guiding piece are corresponding to a shape and size of the sliding slot, the guiding piece comprises a first sliding plate and a second sliding plate connected to the first sliding plate, the first sliding plate defines a step surface formed on where the first sliding plate and the second sliding plate are connected, a connecting pole extends from the second sliding plate substantially perpendicularly, first screw threads are defined on outer surface of the connecting pole, the seat comprises a center portion, a through hole is defined in the seat and passes through the center portion; and wherein the locking assembly comprises a first locking element, the first locking element comprises a first main body and a connecting portion substantially perpendicular to the first main body; characterized in that the connecting pole penetrates through the through hole of the seat; and in that the connecting portion is a hollow structure with a first screw hole defined therein, the first screw hole and the first screw threads of the connecting pole can be coupled, when it is needed to lock the quick release coupling board with the sliding assembly, the first screw hole of the first locking element is screwed with the first screw threads of the connecting pole, and when the first locking element is locked firmly, the step surface of the guiding piece is locked with the blocking sheet. a quick release coupling board; and a sliding assembly configured to be slidably connected with the quick release coupling board; wherein the locking device further comprises a locking assembly, and the locking assembly is connected to the sliding assembly and is configured to lock the quick release coupling board to the sliding assembly, wherein the quick release coupling board comprises: a bottom plate and two opposite side walls, the two side walls each define a sliding slot, each sliding slot comprises a blocking sheet opposite to the bottom plate; a bottom plate and two opposite side walls, the two side walls each define a sliding slot, each sliding slot comprises a blocking sheet opposite to the bottom plate; wherein the sliding assembly comprises: a guiding piece and a seat, a shape and size of the guiding piece are corresponding to a shape and size of the sliding slot, the guiding piece comprises a first sliding plate and a second sliding plate connected to the first sliding plate, the first sliding plate defines a step surface formed on where the first sliding plate and the second sliding plate are connected, a connecting pole extends from the second sliding plate substantially perpendicularly, first screw threads are defined on outer surface of the connecting pole, the seat comprises a center portion, a through hole is defined in the seat and passes through the center portion; and a guiding piece and a seat, a shape and size of the guiding piece are corresponding to a shape and size of the sliding slot, the guiding piece comprises a first sliding plate and a second sliding plate connected to the first sliding plate, the first sliding plate defines a step surface formed on where the first sliding plate and the second sliding plate are connected, a connecting pole extends from the second sliding plate substantially perpendicularly, first screw threads are defined on outer surface of the connecting pole, the seat comprises a center portion, a through hole is defined in the seat and passes through the center portion; and wherein the locking assembly comprises a first locking element, the first locking element comprises a first main body and a connecting portion substantially perpendicular to the first main body; characterized in that the connecting pole penetrates through the through hole of the seat; and in that the connecting portion is a hollow structure with a first screw hole defined therein, the first screw hole and the first screw threads of the connecting pole can be coupled, when it is needed to lock the quick release coupling board with the sliding assembly, the first screw hole of the first locking element is screwed with the first screw threads of the connecting pole, and when the first locking element is locked firmly, the step surface of the guiding piece is locked with the blocking sheet.