A method for optimizing energy consumption of an application program for a DSP includes a program code generating unit is adapted to edit and generate a program code, a program compiling unit is adapted to receive the program code, and according to the program code and the instructional wise energy consumption database generate a plurality of assembly codes, and a DSP simulator adapted to receive the assembly codes and at least one stimulus to simulate the total and the amount of energy every instruction of the assembly codes consumes and transmit the results to the program compiling unit. The program compiling unit modifies the compiling scheme to recompile the program code and transmits the new assembly codes to the DSP simulator, until the simulation results reach or are lower than a predetermined energy consumption value.