This paper presents some of our various test data, newly developed testing method and valuable field data about reliability of Variable Geometry Turbine (VGT) turbocharger. Influential parameters are reviewed item by item.Establishing durability of VGT nozzle and link system is essential for developing VGT turbocharger. However that is not enough to achieve reliability target of VGT turbocharger system only since operating range and conditions of VGT turbocharger is different from conventional system. It was also necessary to optimize other components such as thrust bearing, sealing mechanism and compressor wheel etc. to severer conditions than conventional system.