Ab stract Tube hydroforming process is a relativity complex manufacturing process .performance of this process depends on various factors and requires careful study of part design, materials selection, loading path and boundary condition. Due to the complex nature of the process, forming conditions are mostly simulate and optimized by explicit finite element codes. Usually in THF processes, pressure is applied internally and outward expansion takes place .THF with process with outer pressure is optimized by an explicit FEM code and simulation results were in good agreement with the experimental observation. In this dissertation, first the tube hydroforming process with effective factors has been investigated. Then plastic instability considered for buckling and wrinkling with describing the tube hydroforming for transition piece part. The Abaqus/explicit 6.7-1 has been used for analysis.