Abstract: The rock dredge, as a kind of conventional geological sampling equipment for crust and rock sampling, is widely applied in cobalt-rich crust investigation as well as marine geological survey. This paper made a simple introduction to the equipment with emphasis on the working methods, accuracy control and accident prevention. More discussion is contributed to safety control, success rate, and positioning accuracy for dredging. As a supplement to drilling, it can obtain more bottom samples as well as the cobalt-rich crust.