The invention discloses spatial positioning mechanism design. The spatial positioning mechanism comprises a mechanism body and a driving cylinder, wherein a positioning block is fixed to the upper endof the mechanism body; a fixing block is connected to the lower end of the positioning block; a first positioning pin is inserted into the inner left side of the positioning block; a second positioning pin is fixed to the right side of the first positioning pin; connecting plates sleeve the lower ends of the surfaces of the first positioning pin and the second positioning pin; a limiting block isfixed to the lower end of the fixing block; a first positioning bolt is inserted into the limiting block; a second fixing bolt is fixed below the first positioning bolt; a workpiece is fixed to the upper surface of the positioning block. According to the spatial positioning mechanism design, the first positioning pin and the second positioning pin are clamped into corresponding clamping grooves,thus parts for mounting are decreased due to the clamping type mounting, and moreover, the mounting firmness and reliability can be ensured; in addition, the problem that the first positioning pin andthe second positioning pin are locked while floating up and down due to the error of the driving cylinder and the like can be prevented; the spatial positioning mechanism design is convenient to produce and use, and has a good development prospect.