Abstract: The expansion of farmers' operation scale can be attributed to the combinatorial allocation of factors. As the level of factor marketization keeps increasing, the combinatorial allocation of factors can be achieved through the circulation and substitution of market channels. The findings show that, firstly, it is its natural property that makes the agriculture have absolute dependence on the land, thereby resulting in the fact that the development of the land market or land leasing (transferring) market is the basic conditions for the expansion of farmers' operation scale. Secondly, the expansion of farmer's operation scale is a result of the combinatorial allocation of the factors of land and labor, and the reality of China's agricultural labor flowing to urban areas leads to the fact that the development of agricultural machinery market and the relevant operational service market is a general condition for farmers to further expand their business scale. Thirdly, the constantly improved marketability of land, labor, and their substitutes makes the development of capital (credit) market a threshold condition for farmers to realize scaled operation.

Key words: farmers' operation scale;, stage characteristics, combinatorial allocation of factors, factor bottleneck, market development