The invention relates to an underwater imaging lens, solving the problems of limit effective imaging distance of underwater photography due to luminous energy loss and background interference caused by the adsorbing and scattering action on light by a water medium via the underwater imaging lens in the prior art. The underwater imaging lens comprises an optical system arranged in a sealing mechanism, wherein the optical system comprises a water sealing window, a front lens group, a diaphragm, a rear lens group and an image plane which are successively arranged along a light path incidence direction. According to a great quantity of real experiments, glass combinations are optimized, the focal power is reasonably distributed, 11 pieces of glass are adopted, the lanthanide-series glass material with low chromatic dispersion and high refractive index is chosen, aberrations, such as the spherical aberration, the comatic aberration, the astigmatic aberration, the field curvature, the distortion, the axial chromatic aberration and the vertical-axis chromatic aberration can be effectively corrected, and the imaging quality is improved.