The invention relates to a press fit mechanism which comprises a lifting bottom plate and a lifting mechanism arranged on the upper portion of the lifting bottom plate. The lifting bottom plate is provided with a carrier assembly capable of correcting a carrier and preventing products on the carrier from inclining, an XY adjusting assembly capable of adjusting the X-axis direction and the Y-axis direction of a press fit assembly is installed at the lower end of the lifting mechanism, and the press fit assembly capable of achieving sealing pressing of a screen and a shell is arranged on the lower portion of the XY adjusting assembly. The press fit mechanism can be precisely adjusted and bear press fit force of 17 KN at most, and is compact in structure and low in cost; press fit force can be controlled according to press fit of different products, precision is high, and the press fit and sealing effects are good.