Underwater in-situ filter device

The invention discloses an underwater in-situ filter device which has a simple structure and is convenient to disassemble. The underwater in-situ filter device comprises a water inlet pipe, a watertight shell sleeved outside the water inlet pipe and a water pipe joint which is sleeved on a water outlet of the water inlet pipe and is connected with a water pump, wherein an outer filter screen and an outer filter screen pressing plate which is connected to the watertight shell to be pressed against the outer filter screen are arranged at a water inlet of the water inlet pipe; an inner filter screen is arranged between the water outlet of the water inlet pipe and the water pipe joint; and the water pipe joint is pressed against the inner filter screen tightly by an inner filter screen pressing plate fixed to the watertight shell. According to the underwater in-situ filter device, a water sample is filtered twice, so that the pollution of air bubbles, granules and the like in the water sample to measuring instrum