Abstract: A low power program compiling method includes the following steps: a program to be compiled is received. Wherein, the program includes several instructions to be compiled, the program is executed by an electrical device, which includes several candidate hardware units, after compiled. One of the candidate hardware units is selected as a target hardware unit. Several target hardware instructions, which access the target hardware unit, are detected from the instructions. The target hardware instructions are gathered into a hardware instruction block of the program. An enabling instruction for enabling the target hardware unit and a disabling instruction for disabling the target hardware are inserted before and after the hardware instruction block of the program respectively. The program is compiled after inserted to generate a compiled program.