The invention discloses an optimization method and an optimization device for system parameter design space. The optimization method includes acquiring process parameter data including quality parameters of intermediates of a previous station; selecting the type of key quality attributes according to station production conditions; screening out process parameters related to the key quality attributes as key process parameters; establishing a relationship model between the key process parameters and the key quality attributes; acquiring the design space, namely a specific range corresponding tothe key quality attributes, according to the relationship model. The optimization method and the optimization device have the advantages that the key process parameters related to the key quality attributes are screened out, the relationship model of the two is established, the system parameter design space is optimized, and an effective and reliable solution is provided for parameter release.