Abstract: After initial researching, We can get the conclusion from this Paper that we can realize not only the social welfare-maximization, but also the utility optimality of every consumer Under the fixed condition in socidist market economics of our country. It establishs the mathematical model and gives us the economic meaning and analysis and points out that the point of social welfare-maximization in our country is better than that in other country which has market economics system of complete competition.

Key words: Pareto optimality, Social welfare, Rate of commodity substitution