Abstract: An oil filter includes a housing body, a housing cover, a check valve and a filter core. The filter core and the check valve are mounted in a filtering oil cavity of the housing body. The housing cover is mounted on the housing body and includes a top cover plate and a bottom cover plate. The top cover plate is engaged with the top of the housing body by compressing the outer periphery of the top cover plate to cover the top outer periphery of the housing body. The top cover plate is firmly attached to the bottom cover plate by compressing. The structural strength of the housing cover is enhanced and solves the damage and leaking problems for extending the life of the oil filter.