The invention discloses a PCB two-phase tin stripping method. In the first phase of tin stripping, a SnCl4-HCl system is adopted; and in the second phase, a HNO3-Fe(NO3)3 system is adopted. A specificquantity of tin on the surface of a tin plated board is stripped by first-phase tin stripping treatment; and then, through second-phase tin stripping, the remained tin on the surface of the PCB is stripped to obtain a bright copper plate. After first-phase tin stripping, liquid is pumped in a diaphragm electrolysis system for diaphragm electrodeposition to extract tin and to regenerate a tin stripping agent. Through two-phase tin stripping, the tin stripping speed of the PCB can be guaranteed, tin in the liquid after first-phase tin stripping can be recovered online, and meanwhile, the SnCl4-HCl tin stripping agent can be regenerated. Through second-phase tin stripping by the HNO3-Fe(NO3)3 system, the remained tin on the surface of the PCB can be totally stripped, and the smoothness of the copper substrate can be maintained. The method can effectively solve the problems of high tin stripping waste water quantity and difficult resourceful recycling in a traditional nitric acid system.