Northeast China, especially Heilongjiang province, is developing rapidly as a rising rice-production area.The State Farm, which is a developing entity of paddy fields on the Sanjiang plain near the Sino-Burmese border, has developed several peasant groups with an average business scale of 10-hectare farmland based on well irrigation. Furthermore, both an agricultural-technology system and a mechanization system are being built as the business scale expands. The object of this study is another rice production area in Heilongjiang province, namely, Wuchang City, where the production area for quality rice has been exploited and developed by Korean immigrants since the 1940s. The heartland of Wuchang City is Minle Township. We have already published two papers focusing on the formation of the production area for quality rice and organization problems. In terms of the stability of land leases, this research aims to analyze the business condition of medium and large peasant households from the perspective of technology gaps between different business strata, based on a case study of two large-scale households and three medium-scale households.