Abstract: Institutional factors are essential to the sustainable development of modern agriculture．Using mathematic model to dea1 with the data from 1952 to I995，the contributive rate of the institutional factor to general productive rate in China was calculated．Versatile charac-terlstics of the instituational tsctors affecting agricultural modernization are analysed，and the main cause of the low agricultural development eflieiency,which is the mal-structure of tech-nology induced by institutional structure was pointed out．Finally．it sets forth the adjustment direction of institutional structure in agricultura1 modernization to offer theoretical basis tor the government decision．