Using excitation polarization-resolved second harmonic generation (SHG) microscopy, we measured SHG intensity as a function of the excitation polarization angle for type I and type II collagens. We determined the second order susceptibility (χ (2) ) tensor ratios of type I and II collagens at each pixel, and displayed the results as images. We found that the χ (2) tensor ratios can be used to distinguish the two types of collagen. In particular, we obtained χ zzz /χ zxx = 1.40 ± 0.04 and χ xzx /χ zxx = 0.53 ± 0.10 for type I collagen from rat tail tendon, and χ zzz /χ zxx = 1.14 ± 0.09 and χ xzx /χ zxx = 0.29 ± 0.11 for type II collagen from rat trachea cartilage. We also applied this methodology on the label-free imaging of engineered cartilage tissue which produces type I and II collagen simultaneously. By displaying the χ (2) tensor ratios in the image format, the variation in the χ (2) tensor ratios can be used as a contrast mechanism for distinguishing type I and II collagens.