Compared with the traditional intensity image, the polarization image contains more abundant information of the reflection and scattering of the object surface. The underwater polarizing image was acquired by SALSA camera under natural illumination. The influence of underwater objects, depth, milk concentration and detection band on polarization imaging detection was studied. The results show that in the blue band, the polarization imaging can obtain better information of the boundary contour of the underwater object. The objects of different materials present different polarization characteristics under the water,and the copper has the highest degree of polarization 0.69. Under the condition of milk turbidity 1.40 mg/L, the polarization image can still detect the underwater target by comparing the target object's degree of polarization(DOP) information, the DOP of porcelain only reduces by 0.31. In addition, The image obtained by polarizing imaging is clearer than the intensity image at the depth of about 40 cm underwater. For example, the polarization contrast of iron is 5.26% higher than that of intensity.