Polarization imaging can be used to characterize anisotropic muscle tissue, but the conventional methods can only give the qualitative structure and morphology of muscle development rather than quantitative comparison. In this paper, a quantitative polarization imaging system is constructed. Two perpendicular polarizers are rotated synchronously to get a set of images, and then the quantitative phase retardance of each zebrafish sarcomere is calculated through image processing. This quantitative polarization image is independent of the brightness of light source, the exposure time, etc., hence can be used to compare the morphology and distribution of zebrafish muscle taken at different time. The results revealed differences in the process of muscle growth between wild-type and muscle-damaged zebrafish.