Abstract: New tenancy theory refutes the viewpoint referring to sharing contract being inefficient from conventional tenancy theory. In fact, the error of conventional theory is that it has not considered the risk cost in the real world. So, if the risk factor is uniformed into the transactional costs, the efficiency of sharing contract is also proved. Although the regulation of landlord’s rent revenue right will make rent dissipate, the effect of tenants’ competition becomes an incentive to increase their labor inputs and improve gross agriculture production levels. If the transactional cost is divided into exogenous and endogenous these two types, then we can use them to demarcate efficiency boundary of regulation of land right. And the suitable regulation of land right is a rational choice behavior paradigm in which the opportunist minimizes gross transactional costs under the constraint of resource attribute. Therefore, in terms of evolution history of western physiocracy school, new tenancy theory that based on classic and new classic physiocracy economics brought in transactional costs and risk factor, and created a precedent of new physiocracy economics.