Referring to the problem of impropriety loading in the aircraft static test, the section internal forces were deduced from the shearing force and bending moment and torsional moment of its neighboring sections, and the Lagrange function with internal forces restriction was imported to calculate the loading force in the static test, in order to reflect the aircraft forcing characteristic more reality in the test loading process. Comparing the original internal force before load distribution to the calculating internal force after load distribution, it was known that the internal force calculated from the method of constructing the Lagrange function with internal forces restriction was consistent to the real transferring loading, which satisfies the requirement of the static test, the method can be applied in the aircraft static test.