Abstract: ASIP (application specific instruction processor) design methodology in the design of embedded microprocessors can not only satisfy the functionality and performance requirements of embedded systems but also shorten the lead time of embedded microprocessors. The current ASIP design method confronts many problems, such as architecture optimization and software retargetable compilation. So a TTA (transport triggered architecture)-based embedded ASIP design methodology is proposed, and the key technique in the design is discussed in detail. Also two target applications of ASIP microprocessor design instances are presented to illustrate that this method can effectively solve these problems and quickly develop embedded microprocessors.