The invention discloses a computer mainboard mounting structure. The computer mainboard mounting structure comprises a mainboard body; a connecting plate is arranged at the bottom of the mainboard body; grooves are formed in two sides of the top of the connecting plate; limiting blocks are fixedly connected to two sides of the mainboard body; the bottoms of the limiting blocks run through the inner walls of the grooves and are clamped with the inner walls of the grooves; clamping grooves are formed in one sides, far away from the mainboard body, of the limiting blocks; and supporting rods arefixedly connected to two sides of an inner cavity of the connecting plate. Through mutual cooperation of the arranged grooves, limiting blocks, clamping grooves, supporting rods, movable rods, clamping rods, sliding grooves, sliding blocks, connecting rods, pushing rods, pushing blocks, hollow blocks, sliding rails, sliding rods and springs, the problem of a complex operation process of an existing mainboard mounting structure is solved; and the mainboard mounting structure is simple in operation during use, so that the mainboard mounting speed is increased, the user time is saved, the use convenience is brought for users, and the practicality of the mounting structure is improved.