Abstract: It is an urgent need for sustainable development of agriculture in China to have proper farming scales. To rationally define proper scales for household farms, an index system for comprehensive effect of agricultural land use was built up, consisting of 9 indices concerning society, economy and environment with weights of the indices determined using the AHP and entropy method, in an attempt to analyze and compare comprehensive societal-economic-environmental effect of agricultural land use under different scales of household farms in the Tongting Lake Region. Taojiang County, located in the Dongting Lake Region, was selected for the case study. Results show (1) individuals effect analysis indicates that household farms, >6.67-20.00 hm² in scale, were the highest in societal effect, those, >0.67-2.00 hm² in scale, were in economic effect, and those, >20.00 hm² in scale, were in environmental effect; however, comprehensive effect analysis shows that differently from the angle of the government, household farms, >6.67-20.00 hm² in scale, were the highest in comprehensive effect, while from the angle of the farm households and scholars, household farms, >3.33-6.67 hm² in scale, were the highest in comprehensive effect; and (2) when coordination degree analysis was performed in addition, >3.33-6.67 hm² was held to be the optimal scale for household farms in Taojiang County. Household farms of such a scale were quite high not only in comprehensive societal-economic-environmental effect, but also in coordination degree of the three aspects. All the findings may help find a proper household farm scale suitable to achieving the optimal comprehensive societal-economic-environmental effects so as to realize sustainable development of agriculture.