Optical 3D surface measurement based on structured light illumination has been widely used in machine vision and industrial detection. The structured light 3D measurement is based on the assumption that the surface of the object reflects diffusely. However, most engineering materials do not satisfy this condition, and the influence of the optical properties of the measured surface on the measurement accuracy is often neglected. In this paper, I analyzed and discussed the influence of the optical properties of the surface material on the measurement. The method for calculating and comparing the phase and position of the center of mass of the impulse response is proposed to explain the error that occurs from the use of surfaces with diffuse transmissions and diffuse scattering. I designed a 3D measuring system to obtain the distribution of phase and the position of the impulse response. The results of the comparative experiments show that the optical properties of the measured surface affect the 3D measurement result. It is thus necessary to consider the optical properties of the measured surface in precise 3D structured light measurement.