The invention discloses an assembly type wall mounting support and a construction method. The support is used for mounting an assembly type wall and comprises a supporting frame, supporting columns, abalance frame, a sliding block, an adjusting device and a jacking device. The supporting columns are arranged on the four corners of the support, the supporting frame is a rectangular frame arrangedon the bottoms of the supporting columns, the balance frame is a rectangular frame horizontally arranged on the tops of the supporting columns, the sliding block comprises a bearing part and a slidingbody, the supporting frame is sleeved with the sliding body, the bearing part is arranged on the inner side of the sliding body and used for bearing the wall, the adjusting device is arranged on thebalance frame and the sliding block, and the inner end of the adjusting device is in contact with the wall; the jacking device comprises X-direction jacks and a Z-direction jack, the X-direction jacksare oppositely arranged, the Z-direction jack is vertically arranged, and the supporting frame is arranged on the top end of the Z-direction jack. Adjusting of the wall in the X, Y and Z directions can be achieved, the wall can be precisely mounted in place at a time, mounting quality is improved, the assembly structure is adopted, and dismounting and mounting are rapid and convenient.