A formal semantics is an essential part of modeling languages design as it can help comparison of language designs and provide a precise framework of semantics description. However, it seems that little attention has been paid to formal semantics in the field of evolution process description language. In this paper, the formal semantics of software evolution process description language (EPDL) has been formally given based on the algebraic semantics concept. This paper provides the semantics of EPDL at software process level and global level at first. This paper gives the whole algebraic semantics of EPDL language (ASEPDL).