In order to meet requirements of more photo multiplier tubes working at the same time or in different time, high stability and requirements of voltage intelligent adjustable, the paper introduces the method of Multi-channel programmable photo multiplier tube power supply system using small DC - DC photo multiplier tube power module as high voltage generator. System uses digital potentiometer (MCP42010), linear optical coupler (LOC110) and microcomputer (Atmega16) as the core, including functions of channel selection, control convenient, stable output voltage, output voltage control and so on. The application is writen by C language which has high portability and VB which has graphical programming. With advantages of small volume, light weight, power supply is very suitable for light photo multiplier and photoelectric detection instruments.