Abstract: Involvement time of supplier and information communication among activities is important factors that influence product development time and cost in the inter-organizations collaborative product development.The knowledge accumulation function and rework function are presented based on innovation of activity and importance of downstream activity information.Next,a model is presented about Early Supplier Involvement(ESI)aim for involvement time of supplier and information communication frequency,and a variable of global gain is constructed considering trade-off between product development time and supplier's cost,the existence of maximum of global gain is proved.Based on this,the computing formulas of optimal involvement time and communication frequency is respectively given,and the strategy for Early Supplier Involvement(ESI)is presented.Finally,an example is given to verify the result.

Key words: collaborative product development, knowledge accumulation function, rework function, early supplier involvement(ESI), involvement time of supplier, communication frequency