In order to measure optical element surface defects accurately, a method of optical element surface defect measurement based on the multispectral technique is presented. Incident light sources with different wavelengths are used to illuminate optical element surface uniformly, and defects images are captured by a dark field microscopic imaging system for every wavelength. The multispectral optical element surface defect measurement system is developed. The experiments to detect optical element surface defects and standard test samples are performed under illumination of light with different wavelengths (365, 405, 436, 486, and 550 nm) and white light. The experimental results show that compared with the traditional measurement technology with white light, significant improvement on the measurement performance of optical element surface defects is observed by using the multispectral measurement technique where the wavelength of incident light can be selected according to the material characteristic of tested object. Furthermore, the defect measurement accuracy is improved and many defects which cannot be detected with the traditional method are also obtained.