Abstract: In order to solve the problems of low system efficiency and insufficient economy caused by the high dimensional volatility of environmental data during the configuration of off-grid wind-solar electrolysis hydrogen production system, an optimization study was conducted on the capacity of photovoltaic, wind turbine, and storage battery in typical scenarios. First, a mathematical model of key components including the electrolyzer life model was constructed. Subsequently, scenario generation technology was innovatively adopted to compress the annual environmental data into 12 typical scenarios to reduce the complexity of optimization. Meanwhile, the minimization of levelized hydrogen production cost was taken as the objective function, and the factors of electrolyzer life decay and economic value discount of hydrogen were considered. Based on this, a two-layer nested optimization framework was designed: the inner layer realized the optimal power allocation under each typical scenario based on dynamic programming, and the outer layer optimized the system capacity allocation by particle swarm algorithm. Finally, the environmental data of Basu area in Tibet was used as a scenario case to obtain the optimal configuration under the target hydrogen production capacity of 1 000 m³/h, which verified the superiority of the proposed strategy in terms of system optimization performance and economy.