In applications of CMM (capability maturity model for software), it is a sticking point to implement enforceable software process models, which reflect the characteristics of organizations and their software processes, by transforming CMM software process model. Model driven architecture (MDA) supports model transformation and can be used in CMM practices, but the first step is to build a software process metamodel for CMM. This paper presents a software process metamodel for CMM based on SPEM(software process engineering metamodel), named SPM-CMM. SPM-CMM provides abstract syntaxes and rule semantics for CMM software process, and also supports of modeling of CMM integration with UML CASE tools.