In order to solve the tediously calculative problem of deflection and finite element analysis of the pedestrian suspension bridge under vertical load, a simplified calculation method was proposed by considering the flexible structure of pedestrian suspension bridge, neglecting the stiffness of the stiffening beam, and considering the IP displacement of the main cable, the cable sag effect, and the geometric nonlinearity. The stress-free length and midspan deflection of bridge main cables with different spans and different rise-span ratios were calculated, and the application scope and error of the simplified calculation method were analyzed based on the results of the trial calculation. The calculation accuracy and application scope of the method were verified. Taking a pedestrian suspension bridge with a span of 117 m as an example, the mechanical properties of the suspension bridge under completed and vertical load state were analyzed by the calculation method in this paper, and compared with the results of finite element analysis and test. The results show that the simplified calculation method proposed has good practicability and can provide a reference for the rapid solution and verification of finite element analysis result of pedestrian suspension bridges in practical engineering.