Mariculture industry, makes great contribution to national food security, economy and trade balance. To realize sustainable development of mariculture in China in the new period, it is urgent to exploit new space and develop offshore aquaculture strategy. Offshore aquaculture is an integrated system including suitable species, culture techniques, culture equipments, energy supply, sea-land relay logistics, aquatic products processing, and strategies of disaster prevention and reduction. On the basis of a strategic concept of the new space for mariculture in China, the present study puts forward strategic missions on the development of offshore mariculture. The missions include building a suitable species breeding and efficient farming technology system, constructing a new type of marine fisheries production mode with the core of offshore aquaculture platform, building an energy security system, and constructing an intelligent mariculture products logistics network. Based on these strategies, relevant policy suggestions are also suggested.