The invention discloses a method and a device for generating master-salve servo system synchronous signals, and a lamp detector. The method for generating the master-salve servo system synchronous signals comprises the following steps that: a master servo system and a slave servo system receive control information sent by a virtual main shaft respectively; the master servo system and the slave servo system track the virtual main shaft according to the control information, and generate a master position following error and a slave position following error respectively; a judging module judges whether the master position following error and the slave position following error are in accordance with a predetermined condition; when the master position following error and the slave position following error are in accordance with the predetermined condition, a synchronous signal generating module generates the synchronous signals. By the invention, the position errors between the master and slave servo systems are small; the master and slave servo systems are synchronized; and the false inspection rate of the lamp detector is reduced.