The invention relates to the technical field of test machines, and in particular relates to an electro-mechanical continuous stepless amplitude modulation linear actuator. The actuator comprises a machine body, a main power source transmission mechanism, main, left and right slider-crank mechanisms, a wedge traction mechanism and a traction power source transmission mechanism. The main power source transmission mechanism and the traction power source transmission mechanism are connected with the machine body. A square shaft in the main power source transmission mechanism is connected with a machine body bearing. Main, left and right eccentric discs in main, left and right slider-crank mechanisms are provided with inner holes, wherein the square shaft passes through the inner holes. The wedge traction mechanism is connected with the right slider-crank mechanism and the traction power source transmission mechanism. The traction power source transmission mechanism is fixed on the machine body. According to the invention, the movement of the mechanisms which are driven by a control motor directly acts on a test-piece; the electro-mechanical continuous stepless amplitude modulation linear actuator has the advantages of large output load, high operation frequency, being maintenance-free, high efficiency and significant energy saving; vibration caused by the main slider-crank mechanism is reduced; and the length of a crank can be continuously adjusted.