Vehicle launch shudder is the terminology used in automotive industry to describe the severe longitudinal oscillation during clutch engagement under condition of starting-up. This paper presents and implements detailed investigation for the process of dry-clutch engagement, in order to deeply analyze vehicle launch shudder phenomenon which seriously deteriorates ride comfort. A mathematical model is established to reflect nonlinear relationship between the displacement of release bearing and the frictional torque transmitted by dry-clutch. This model takes into considerations the axial compression characteristics of three elastic parts, including diaphragm spring, cushion spring and link strip, meanwhile relates to the variation of friction coefficient of friction disc linings versus the sliding speed. Based on dry-clutch torque transmissibility characteristic, torsional vibration model of vehicle driveline is set up according to the parameters of the certain compact vehicle, aimed to simulate the launch shudder phenomenon numerically and study the mechanism of friction self-excited vibration. A reasonable experiment program is designed for launch shudder and implemented on the vehicle equipped with manual transmission under different starting conditions. The characteristics of launch shudder are identified from the experimental data by power spectral density analysis and time-frequency analysis. Compared with the simulation results and the experimental results, it is found that the variation tendencies of launch shudder characteristics of the both are consistent, and the validity of torsional vibration model of vehicle driveline is proved, then analysis of factors influencing launch shudder evaluated by shock are done based on simulation model. Through the research of this paper, the launch shudder during the process of dry-clutch engagement is analyzed, which can provide theoretical references for the subsequent structural optimization and the engaging control strategy of automatic transmission.