Abstract: This article researchs the questions of enterprise development which take the tendency of enterprise life period as its goal. Talks the basic method of enterprise development——to large the enterprise mode and analyses two factors which affect enterprise mode: time and increase rate. On this basic, it also analyses the methods of enterprise development, points out the limity of large in enterprise mode to the enterprise development and gives the major stretragy of enterprise development which is diversification. This whole thinks: why the diversification is the major strategy of enterprise development, the reason lies in that the life period of entriprise development and the product life period are connected with the field life period. The major limited factor of product diversification and field diversification comes from the technical limitity.