Urinary catheter has been widely used as a solution for urinary incontinence problem. But it can induce pressure stress at the human bladder neck. However, owing to the complexities in balloon geometries, material properties and interactions in bladder, analyses of the complete stress inflation of balloon are limited. This study describes some numerical simulations of the expansion phase of catheter balloon on bladder and to study the stress distribution at the balloon. In order to investigate the mechanical characteristics of inflation catheter balloon, a three-dimensional model of the complete catheter balloon were developed, which made the simulation well close to the real situation. Finite element analysis (FEA) ABAQUS 6.4-PR11 was used to simulate the balloon inflation and deflation. The hyperelastic behavior of the Mooney-Rivlin model is considered. Mechanical properties of the balloon have been taken from the literature. Simulated results showed that the stress distributed on the surface of the balloon. The maximum Von Mises stress for natural rubber from the analysis is 5.11 MPa. High stress concentrates on the center of it. In conclusion, FEM can help illustrate and quantify some mechanical characteristics of the balloon and it would be helpful for the general understanding of inflation of urinary catheter balloon.