Based on the practical needs of multi wavelength wave front detection testing technology,an optical structure of multi wavelength laser interferometer was designed.Based on the Fizeau interference principle,the structure uses a splitter prism to integrate 5 wavelengths of laser light sources.The coaxial error of each part of the optical structure is reduced by the cage system,and the achromatic lens is used as the collimating system and imaging system of the interference system,which can shorten the travel of the collimating system and reduce the color difference of the optical system inside the system.The Zernike coefficient and wavelength curves calculated by the conversion polynomial method are in good agreement with the predicted results.The optical structure of multi wavelength laser interferometer improves the testing efficiency of multi wavelength transmitted wave front,which is conducive to the engineering and popularization of multi wavelength transmitted wavefront testing technology,and provides a reference for the development of new instruments.