Abstract: Model transformation language is the key to the implementation of MDA, it needs a clear and complete transformation language 〖JP2〗in the whole system of MDA. First analyzes characteristics of model transformation language and situation of the today’s〖JP〗 major model transformation languages. Then makes the theory analysis of OCL as model transformation language. On the basis of the analysis, extendes the object constraints language. At last, gives the framework to model transformation by OCL. 

Key words: MDA, OCL, MOF, QVT, MTF, model transformation language