In order to reduce the cost of offshore oil and gas exploration and development in the Arctic, it is required to develop equipment capable of operating in the Arctic. A new concept of semi-submersible drilling platform which can be used for offshore drilling in the Arctic is proposed. The platform is composed of six columns and two pontoons, and the upper part of the platform column is designed as an inclined form to reduce the ice load acting on the platform. To ensure the broken sea ice does not affect the drilling operation, the platform is designed with riser protection fence and ice resistance cover for anchor chain. The design conditions, main dimensions and mooring system design of the platform are introduced. The mooring positioning capacity of the platform is analyzed in summer and ice season by commercial software. The analysis results show that: the semi-submersible drilling platform can finish the drilling operation in the open water season and ice covered season in winter; the platform can maintain operation capacity under the action of 1.0 m thick sea ice and survival under the action of 1.5 m thick sea ice; the mooring and positioning capacity of the platform meets the requirements of Arctic drilling operation.