Abstract: CDL is a wide-spreading computer hardware description language. CDL/MP is an ex pausion of the CDL. This paper presents a Computer Aided Microprogram Development System using CDL/MP which consists of Microprogram Assembler (MA) and Microprogram Simulator (MS). A common machine description (in CDL/MP) is used by MA and MS, and a subset of CDL/MP is utilized to describe the microprogram algorism. The design of CDL/MP and the structure and imple mentation of the system are introduced.