Since the electronic shift lever detent system is used in vehicles on a large scale, it is urgent to solve the problem of robustness parameter design of the shift quality of SLDS under the uncertain dynamic parameters and manufacturing tolerances. We Build the MBD model of shift lever detent system, selecte the evaluation indicator for shifting quality and propose a two-stage method which associates the deterministic optimization of grey relational grade with the robustness parameter optimization of six sigma, in the early stage of product quality design. We use the grey relational grade to take the place of SNR in deterministic optimization, and compute the the optimal combination of controllable factors and their levels. The controllable parameters of shift lever detent system include three parameters that determine the detent profile structure parameters, spring parameters and contact pair parameters. The deterministic optimization of grey relational grade provides initial values for the six sigma optimization, and the six sigma optimization solves the problem of tolerance design of controllable factors under the uncertainty of noise factors in further. The test results of the experiment validate the rationality and correctness of the MBD model of shift lever detent system, the selected controllable parameters, and the two-stage optimization method. The results also prove these models, parameters and methods, which can solve the problem of robust design of the shift quality. What's more, The two-stage method proposed in this paper is more applicable to the problem of dynamic robust design with discrete-continuous parameters.