To realize product self-organized evolution innovation that is driven by knowledge, the method of ontological expression of product innovative knowledge and integrated reasoning technique are researched. Ontological knowledge system that drives product self-organized evolution innovation and its expression model were built. The expression manner of ontological knowledge based on STEP was discussed, and it was implemented by instantiation of ontological knowledge. The knowledge-based reasoning technique was adopted to transform dada to driven rules, so as to bring innovative product scheme; the case-based reasoning was used to match corresponding structure scheme. The knowledge base and rule base for circuit breaker development were set up, and self-organized evolution innovation of its mechanism system was accomplished. Applied example shows that ontological expression method of the knowledge and integrated reasoning technique with maneuverability and practical value can satisfy requirements of self-organized evolution innovation that is driven by knowledge.