Abstract: Turbocharger VGT60 was applied to diesel engine YN4100QBZ, forming a test bed set up, and test procedures were determined. Systematic and comprehensive tests were conducted using the VGT's real time monitoring system. Test data of various conditions were analyzed, and comparison of emission characteristics made to the original engine. Influence characteristics and rules of VGT to the diesel engine under steady conditions were derived, and the influence of the VGT to the smoke emission of the diesel engine under free acceleration conditions tested. These provide basic data and strategy for the control and optimum matching of VGT to diesel engines on all the conditions.