An installation tool and method for spherical latticed shell structure is provided. The spherical latticed shell structure includes a plurality of latticed shell units. The installation tool includes a support frame, a hoisting system, a fixing frame and stay rope assemblies. The support frame is arranged on one side of a to-be-installed spherical latticed shell structure. The fixing frame is connected with the hoisting system. The hoisting system is arranged on the support frame for hoisting the fixing frame. The stay rope assemblies are connected with the fixing frame and the latticed shell units.