A linear actuator comprises a housing, inside which a spindle assembly, a push rod assembly driven by the spindle assembly, a limit switch for limiting stroke of the push rod assembly, and a motor for driving the spindle assembly are mounted. A connecting seat is disposed on the circuit board for centralizing connection terminals. The motor is electrically connected to the connection terminals. The housing is provided with a plug-in window aligned to the connecting seat. An electric plug of the linear actuator passes through the plug-in window and is plugged into the connecting seat. The electric plug and the housing are fastened together via a mounting component.