A point on the distinction between design and science is given and the connotations of design science are discussed in the paper. Design should be understood as the first step of all human's purposeful activity,which is a daily behavior for everyone. Four laws are summarized,which describe the basic patterns of design and are the constituents of design science. They are the law of design based on existed knowledge,law of incompleteness of design knowledge,law of design centered on new knowledge acquirement and law of competitiveness of design knowledge. The four basic laws show the knowledge essence of design. To enrich the existed knowledge,to make it convenient to be used,to teach designers with high intuition and inspiration in picking useful elements of existed knowledge and shaping competitive ideas and to have strong new knowledge acquirement facility are the basic conditions of good designs. Study of design science will promote the structure of traditional engineering education. An important conclusion is derived that there will be no successful innovation without good design.
