Abstract: Because of the absorption and scattering effect of water, it is always very difficult to explore under water with common light source. With advantages of the characteristics of laser, the absorption and scattering effect of water is reduced. Taking He-Ne laser as the light source, the reflection coefficients of the objects were detected in the air and underwater to make sure the feasibility of underwater exploration with laser. It is found that the experiment result is good after comparing the detected results with the reference data.