The invention relates to an automatic blanking and installing method and automatic blanking and installing equipment for diaphragms of alarms of motor vehicles. By a diaphragm automatic blanking device, the round diaphragms are blanked upwards from a continuously transferred strip raw material tape through a punch of the blanking device; then the blanked diaphragms are automatically sucked and placed at designated positions on an alarm diaphragm installation line by a suction die on a mechanical arm on a diaphragm transfer device; one work period is from the moment of blanking one diaphragm to the moment of placing the diaphragm to the designated position; a plurality of work periods are continuously and circularly carried out; the whole process is automatically controlled by a central control computer. The design structure has the beneficial effects that two original steps of diaphragm blanking and diaphragm installation are combined into one step; automatic blanking and automatic installation are implemented; labor is saved. In the working process, blanking and installation of the diaphragm are sequentially carried out, so that installation quality is ensured and the phenomenon of excessive installation or neglected installation cannot be caused. Compared with the original manual blanking and assembling method and equipment, the automatic blanking and installing method and the automatic blanking and installing equipment have the advantage that efficiency is doubled.