This paper presents an analytical approach to analyze the vertical vibration of a simply supported beam subjected to pedestrian-induced loads. The loading time history of an individual footstep is simplified as a rectangular force pulse, and each identical footstep load acts at different locations along the beam depending on a step length. Although the loading model is very simple, it enables us to find analytical relations between the pacing parameters and the beam response. The results showed that the dependence of the pacing period, footstep contact duration, time delay of traveling between two pedestrians on the natural period of the beam as well as the step length can influence the dynamic response of the beam significantly.