This paper introduces the assumption of asymmetric utility between differentiated and non-differentiated products,and embeds it in a utility function and Cournot equilibrium model. At the same time,the isoperformance constraint condition and the constraint condition of demand price elasticity are introduced to establish and solve a nonlinear programming model,from which a cost leadership strategy theorem is deduced.Then,theorems regarding the relations between cost-utility,outputs and prices of two pure strategies are given. Further,this paper deduces the financial identification conditions for the two pure strategies,and gives an analytical proof for Palepu assumptions. Finally,a strategic premium theoremis given. The research indicates that cost leadership strategy is endogenous,and that the cost-leaders' product features lower-cost and lower-utility,higher-output,lower-price relative to the differentiator's. The results show that the ratio of the cost-leader's product price to the differentiator's is lower than the ratio of the cost-leader's product cost to the differentiator's. The results also show that the necessary-sufficient conditions of pure strategy identification are that the cost-leader features lower operating-profit-ratio and higher asset-turnover-ratio relative to the differentiator,and that the differentiator features the opposite,asis in accordance with Palepu assumptions. Finally,the results show the Porter premium condition is incorrect.