The important trait of industrial clusters is that the course of production of the end consumptive goods is decomposed some manufacture taches for the middle products, that are produced and assembled by those specialized firms, and the trade of the middle goods between firms must follow the rule of market competition. The substantial characteristic of industrial clusters is to gain more efficiency for production and innovation by the knowl- edgepartitioning in the interfirm. But the knowledge partitioning may partly cause kinds of knowledge risk, including knowledge homogeneity risk, knowledge dependence risk, and knowledge matching risk. The evolution of industrial clusters is determined by the knowledge partitioning and its changing direction in the interfirm, and the course of evolution is divided into four phases, including startup, forming, extending, and maturing.