Based on firefly algorithm (FA), a novel method is proposed for moving force identification (MFI) in this paper. The basic principle of FA is introduced, some key parameters, such as light intensity, attractiveness, and the rules of movement are defined. The inverse problem on MFI is transformed into a constrained optimization problem and then can be hopefully solved by FA. In order to assess the accuracy and the feasibility of the proposed method, a beam-like truss bridge subjected to moving forces is taken an example for numerical simulation. The robustness of the method is also evaluated by adding noise into the structural responses. The illustrated results show that the proposed method can accurately identify two moving forces from incomplete structural response at only one strain sensor with stronger robustness.