The invention discloses a power system model interface and a power system model splicing method applicable to a non-mechanism model, and belongs to the field of power system modeling. The power grid non-mechanism model provided by the invention deduces a power load transfer function model based on unbalance of flow of a power grid to be spliced, and then the non-mechanism model of the power grid to be spliced when in splicing of the whole power grid is deduced to serve as an interface model when in splicing, and thus spicing of the whole power grid is achieved. The power system model interface provided by the invention is applicable to a radiation type network or star-type network, the unbalance of flow when in power grid splicing can be solved, the problem that a boundary flow matching algorithm based on sensitivity correction is low in efficiency is solved, the problem that when a flow difference between internal and external networks is large and even does not converge is solved, and meanwhile the problem that the non-mechanism model is accessed via the model interface is solved.