FEM analysis has become an important tool for the design of aircraft. In order to improve the accuracy of FEM simulation, it is necessary to modify and update the FEM models. This paper took a global FEM of some helicopter as subject, based on strain response measured in static test experiment, a variable sensitivity analysis and model updating were performed. Because of the big numbers of measure points of the test and the huge degrees of freedom of the global FEM, and a new dependency arithmetic which was suitable for global model was firstly given. Based on the arithmetic and combined with the results of some test case, partial parameters of the global FEM were updated to attain a better conformance with the test results. At last, a verification with results of other load cases were performed and a conclusion was given that the conformance between test results and simulation results after the global FEM updating in other cases were also promoted as predicted, which proved the feasibility and effectiveness of the dependency arithmetic and the process of global FEM optimization.