Axiomatic Design has been developed as a general design framework during past two decades and TRIZ has been developed for a design tool over 50 years. Axiomatic design is quite excellent in that the design should be decoupled. When a design matrix is established, the characteristics of the design are identified concerning the coupling properties. If the design is coupled, a decoupling process should be found. However, axiomatic design does not specifically indicate how to decouple. In this paper, a design method is developed to use TRIZ in the decoupling process. The decoupling ideas are extracted from the substance field analysis and various methods in TRIZ. The mettled is applied applied to the conceptual design of a beam splitter for the laser marker and the results are analyzed.