Taken a semi-submersible lifting dismantling platform equipped with two 2 200 t crane on the starboard side as an example, the stability calculation model is set up to simulate the crane load conditions. The transverse and longitudinal changes of the platform under three working conditions of bow crane, stern crane and combined crane are analyzed. The platform is leveled by means of rapid load adjustment. The loading scheme after leveling is given, and the stability under different working conditions is analyzed. The results show that the stability of the combined operation of cranes is poor and the stability of the platform can be improved by reducing the center of gravity.