The invention relates to a water pump type floating and diving mechanism. The mechanism comprises a front water tank and a rear water tank, wherein the front water tank is connected with a first waterinlet drainage pipe, and the rear water tank is connected with a second water inlet drainage pipe; the mechanism further comprises a liquid level adjusting device, wherein the first water inlet drainage pipe and the second water inlet drainage pipe are correspondingly connected with and communicate with the liquid level adjusting device, and the liquid level regulating device communicates with the outside; and the liquid level in the front water tank and the rear water tank is adjusted through the liquid level adjusting device. According to the mechanism, a water tank is divided into the front water tank and the rear water tank so as to fit the internal shape of underwater equipment on one hand, the longitudinal balance of the underwater equipment can be adjusted through mutual flow of liquid in the front water tank and the rear water tank on the other hand, and floating, diving or longitudinal balance adjustment of the underwater equipment equipped with the mechanism can be realized.