A meshing-type rubber internal mixer and a working method thereof are provided. The meshing rubber internal mixer includes a frame mechanism, a mixing mechanism, and an unloading mechanism. The mixing mechanism is on the upper side of the unloading mechanism. The mixing mechanism and the unloading mechanism are in the frame mechanism. An internal mixing chamber is of a closed structure through first automatic telescopic plates and second automatic telescopic plates. The gap between a first meshing-type rotor and a second meshing-type rotor is small, a material is compressed to enter the space between the first meshing-type rotor and the second meshing-type rotor to be extruded with an internal mixing chamber wall. The material is flaky in the internal mixing chamber, so that the material produces great strain deformation, thereby achieving excellent dispersing and mixing effects.