Marx did not directly discuss rural surplus labor force but, in his Research on Capital, he pointed out that machines would reduce the number of employed workers when organic composition of capital was increasingly promoted. According to Chinas situation, the appearance of rural surplus labor force results from scarcity of rural land and the slow growth of absorbing ability of labor force of non - agriculture sectors. The cause for the factors of scarcity of agricultural land is scarcity of agricultural land and surplus labor force and is that incomplete property right of rural land leads to high transaction cost of agricultural land so that a lot of agricultural land is wasted.