According to the problem that it is difficult to generate white noise and some other speaker power test signals in C++ Builder and the problems of compatibility in mixed programming between Matlab and C++ Builder, a mixed method combined Matlab with C++ is put forward. Firstly, a dynamic link library DLL is generated in Matlab. Then, VS calls the DLL file and writes interface function to create another DLL file which can be used in C++ Builder. Finally, design the application program to generate the speaker power test signal in C++ Builder. To verify the accuracy of the generated signal, some parameters of signal are calculated, such as the mean, variance, self-correlation, spectrum and power spectral density, the probability density and RTA of one third octave. Comparing the calculated results with the standard signal's, it shows that the signal generated by mixing programming can be used for speaker power test.