Abstract: Taking proportion of task assumed by supplier involved into collaborative design as the quantitative index of his participation degree,considering R&D uncertainty,we seek the optimizion participation degree from supplier's point of view.Result shows,for the supplier,its participation is restricted by two sides' relative marginal profit,development ability and market uncertainty of the new product.When supplier involves and shares some manufacturer's design task,he has an optimized proportion to choose,this proportion positively related to its marginal profit and technology development ability,negatively related to manufacturer' marginal profit and technology development ability,as well as to market success probability.

Key words: uncertainty, supplier involvement, collaborative design, decision