In order to solve the challenges of grid integration and high power transmission costs in the large-scale development of offshore wind power to the deep sea, on-site wind power hydrogen production and hydrogen based chemical engineering at the deep sea wind farm is an effective approach. In order to refine the design of offshore hydrogen production and hydrogen energy conversion process flow, improve the design and construction efficiency of offshore hydrogen production and hydrogen energy conversion platforms, simplify the design interface and improve operational safety, this paper choses a certain type of semi submersible support platform as the target platform. Firstly, the process flow design of offshore platform hydrogen production, hydrogen to methanol production, and hydrogen to ammonia production was carried out; Then, hydrogen production and hydrogen energy conversion module division and process system layout design are carried out on the main deck of the target platform which the overall process flow, module functions, platform weight, and safe operation of the platform were taking into account; Subsequently, safety risk analysis and evacuation plan planning were carried out for the layout scheme, maximizing the safety of platform operation. The design results well meet the expected requirements, and realize the demonstration operation of offshore hydrogen production and conversion, which provides a reference for the transformation design of related platforms.