The spring grid deforming method is introduced into CFD/CSD coupling analysis, and a CFD/CSD loose coupling method is developed for rotor aeroelastictiy analyses. In order to solve the key problem of grid deformation in CFD/CSD coupling method, the dynamic grid method based on ″ball-vertex″ spring system is introduced in rotor body-fitted grid deformation. By adopting the necessary constraint springs, the new grid deforming method avoids distorted grid cells. The rotor flowfield is solved by using a CFD module based on Navier-Stokes(N-S) equations and overset grid technology, and the B-L turbulent model is employed to resolve the viscosity. The CSD module is established based on moderate deformed beam theory and Hamilton′s variational principles. The CFD module and the spring grid deforming module are tested by predicting the airloads of oscillating NACA0012 airfoils while the CSD module is validated through analyzing the blade resonance frequency of the UH-60A rotor. The airloads on the UH-60A rotor blade are calculated and compared with flight test data. By the comparisons of the results calculated by CFD/CSD method with results calculated by rigid CFD method, it is demonstrated that the present spring grid deforming system can be effectively used in the CFD/CSD coupling method and improve the prediction accuracy of the airloads of the rotor.