The invention relates a submerged type double-pump trimming system. The submerged type double-pump trimming system comprises a stern water tank and a bow water tank. The stern water tank and the bow water tank are connected through a general pipe. A first water pump and a second water pump are connected to two tail ends of the general pipe respectively. A first branch pipe and a second branch pipeare in parallel connection with two ends of the general pipe respectively. Tail ends of the first branch pipe and the second branch pipe are connected to the stern water tank and the bow water tank respectively. A first valve is arranged on the first branch pipe. A second valve is arranged on the second branch pipe. A flowmeter is arranged in the middle of the general pipe. The tops of the sternwater tank and the bow water tank are connected to a plug valve through pipelines. A silencer is arranged on a pipeline. According to the submerged type double-pump trimming system, improvement of water transferring efficiency is benefited; the water transferring speed is high, and the water transferring precision is high; the system is not limited by the length of equipment, neither; and the system is applicable to deep sea equipment with medium-scale displacement.