A linear actuator includes a housing (100), a base plate (200) disposed in the housing (100), and two actuating mechanisms (310, 320) disposed on the base plate (200) and received in the housing (100). Each actuating mechanism (310/320) comprises a motor (311/321), a transmission assembly (312/322), a screw rod (313/323), and a supporting block (314/324). Two motors (311, 321) and two transmission assemblies (312, 322) are disposed on the base plate (200). Two motors (311, 321) are kinetically connected to two assemblies (312, 322), respectively. One end of the screw rod (313/323) is connected to and rotated by the transmission assemblies (312/322). The other end of the screw rod (313/323) is screwed to the supporting block (314/324). Thus, two supporting blocks (314, 324) are driven to move in the housing (100).