In order to analyze the Dynamic Positioning Capability (DPCap) of the semi-submersible platform under the combined action of ice, wind, wave and current, the finite element software LS-DYNA is used to build a numerical model of ice load, and the ice force time course curves are obtained for different ice-welcoming angles with semi-submersible platform as an object. Based on the self-developed DPCap analysis program, the ice load is incorporated into the environmental load, the DPCap of the platform in broken ice area is calculated and the DPCap curves are drawn. The working window of the platform in operating sea conditions is observed, and it is found that the ice loads of the broken ice area are of great influence on the DPCap of the semi-submersible platform, and the impact is most obvious when heading in . The DPCap of the semi-submersible platform is evaluated in combination with the failure condition of the propeller, and the DP scheme when the platform encounters the broken ice area and the suggestions for the design of the propulsion system are proposed.