This paper presents a silicon wavelength multiplexer based on Mach-Ze h nder Interferometer.The device can control the transmission spectrum of each ch annel by the integrated electro-optical phase shifter to compensate the wavelen g th drift caused by the external temperature conversion and process error.The me asurement results show the efficiency of the phase shifter is 3mW/π and it can r ealize four wavelength division multiplexing.The channel spacing is 3.3nm and the isolation is more than 30dB.