The invention relates to a three-structure-state transformation space deployable mechanism based on scissor units. The three-structure-state transformation space deployable mechanism based on scissorunits is formed by scissor units, hinges and chassises, wherein the scissor units can be converted into a first structure-state, a second structure-state or a third structure-state through unfolding or furling; the first structure-state is a triangular prism structure-state; the second structure-state is a quadrangular structure-state; the third structure-state is a pentagonal prism structure-state; the hinges include a double-revolute-pair hinge and a three-revolute-pair hinge; and one end of the double-revolute-pair hinge is connected with the chassises through pins, and the other end of thedouble-revolute-pair hinge is connected to the scissor units through pins. The three-structure-state transformation space deployable mechanism based on scissor units has the advantages of being lightin weight, being single in the component type, being large in the folding ratio, being small in the furled volume, being stable in mechanism deploying, and having variable three structure states, being able to be used as a polygonal space folding unit, and being suitable for an aerospace support frame and a planar transmitting antenna.