Affect factors of spring-back for C-shaped composite spars generally include geometry, shear effect between plies, and mold, et al.The factors often bring to process-induced distortion in compositestructures which would lead to bad geometric accuracy.Through analyzingthe factors by theory approach, the FE calculation and experiment method, the spring-back values of C-shaped spars in structures of aircraft are calculated and the weight values of the factors are also estimated, which could be used to provide some bases for distortion prediction and control for C-shaped composite spars.