Based on the framework of social cognition theory and planned behavior theory, the principal component analysis method, Heckman two-stage model, and comparative analysis method were adopted using 379 farmer survey questionnaires from three counties (districts) of Wulian, Dongping, and Kenli in Shandong province. The purpose is to explore the main influencing factors, mechanism and difference of farmers' scale management willingness and behavior, and to provide decision-making reference for promoting the moderate farmland scale management. The results showed that: (1) The degree of cognition of land policy by farmers interviewed is generally low in the case study areas, and there are regional differences in the level and structure of cognition. (2) The individual characteristics, resource endowment and location factors all have significant effects on the scale management willingness, while the influences of policy cognition and social security are not significant. The individual characteristics, resource endowment, policy cognition, social security and location factors all have influence on scale management behavior. Among them, the factors that have greater effects and pass the significance test are whether to participate in agricultural insurance and the cognition degree of new business entities. (3) Some 27.70% of the farmers interviewed have inconsistency between scale management willingness and behaviors. There are some differences in the scale management influencing mechanism between mountain and plain farmers, and there are many differences in the factors affecting the farmers' willingness and behavior. (4) It is necessary to thoroughly understand the level and structure of farmers' policy cognition, strengthen publicity and education in a targeted way, build information platforms according to local conditions, reduce transaction costs for the transfer of agricultural land, and build an agricultural socialized service system for small farmers to realize the dual scale of "land + service".