The problem of choice of strategic alhance forms under different co-competition modes is explored using an approach of more-stage game in this paper. We show that only cooperation in the R＆D stage is enterprise＇ s choice from the view of maximum output of industry. According to minimization of R＆D expenditure, noncooperation at both R＆D stage and product ＆ marketing stage is reasonable choice for enterprises. From the aspect of maximum industry profits, if the profit of cooperation at both stages is more than that of only cooperation at the R＆D stage, the forms of cooperation in both stages will be feasible for enterprises, whereas, the only cooperation form at the R＆D stage is feasible for enterprises. In terms of maximum enterprises＇ profits and minimum R＆D expenditure, after selecting cooperation at the R＆D stage, the enterprises may select leading cooperation strategy with other firms at the product ＆ marketing stage