Assembly device and assembly method of cross axle joint

The invention discloses an assembling device for a cross shaft joint. The assembling device comprises a base, a spline shaft assembly positioning mechanism, a flange fork, a cross shaft positioning mechanism and a turnover driving mechanism. The spline shaft assembly positioning mechanism, the flange fork and cross shaft positioning mechanism and the turnover driving mechanism are all installed on the base, and the turnover driving mechanism pushes the flange fork and cross shaft positioning mechanism to rotate to achieve conversion between the horizontal state and the vertical state. The invention further discloses an assembling method of the cross shaft joint. Vertical assembly of the spline shaft assembly and the cross shaft is changed into horizontal assembly, and potential safety hazards are greatly reduced. Assembling of the flange fork and the cross shaft and assembling of the spline shaft assembly and the cross shaft are completed in the same device, a traveling crane is used for hoisting at the begin