Based on the contradiction between highfragmentation of China’s land and rapid development of agricultural mechanization, by using the microscopic investigation data of 11 provinces, this paper analyzes land fragmentation effects on household investment in agricultural machinery socialized service. The study finds that the land fragmentation has seriously restricted the ability to provide agricultural machinery socialization service. In addition, the improvement of the convenience of agricultural machinery operation can in a certain extent offset the adverse impact of land fragmentation on agricultural machinery socialized service. The realization of the convergence of crop planting structure and planting technology in the different lands with the business right of different farm households can expand the work area under unchanged present condition of land fragmentation and can help to share economies of scale among neighboring households, and can improve the convenience degree of the agricultural mechanization, so as to encourage agricultural households to invest in agricultural mechanization services. This paper argues that in order to increase the operation area of land to promote land scale management in order to encourage adjacent farm households to work together, it is more conductive to improve farmers’ access to land scale economy of availability and to promote the investment of agricultural machinery socialized service.