Abstract: In this paper, we define the residual force vector as a structure damage index,and give the detailed theoretical derivation for residual force vector according to the structure eigenvalue equation.Takinga simple supported truss as a research target, we carry the local damage identification of truss by use of residual force vector,and identify the single and multiple local damage of truss structure.We further explore the impact of noise on the accuracy of damage identification by introducing damage localization index and considering the existence of noise in actual measurements. Theoretical analysis and numerical results show that the residual force vector can identify local small damage of the truss structure beam effectively and have good noise immunity.