The invention belongs to the technical field of heat management of electric automobiles. Power of the electric automobile is supplied by a battery pack which is provided with a cooling system and equipped with multiple batteries, and cooling of the electric automobile is generally based on liquid cooling, but in the working process, some impurities in cooling fluid may affect the normal circulating flow of the cooling fluid and reduce the cooling effect on a power battery, thus affecting the normal work and the service life of the battery. In order to solve the problem, the invention provides a filter which mainly has two functions of 1, filtering iron-containing impurities in a cooling fluid loop of the power battery through a filter element, so as to avoid the influence on normal flowing of the cooling fluid due to deposition of the impurities on the power battery pack or a circulating pump body and enhancing the liquid cooling effect of the power battery, and 2, when blocking is caused by more impurities deposited on the filter element, automatically switching on a spring valve under the action of a pressure difference between a water inlet and a water outlet to enable the cooling fluid to directly flow from the water inlet towards the water outlet, so as to avoid poor battery cooling effect caused by no flowing of the cooling fluid due to the blocking of the filter element and improve the working safety of the power battery.