Momentum wheel (MW) is a critical component in satellite attitude control systems. Its remaining lifetime has a direct impact on the reliability and the useful life of an on-orbit satellite. A lifetime prediction method based on multiple degradation parameters is proposed. Key factors connecting to the MW′s lifetime are analyzed. The lubricant remaining amount and current are selected as two degradation parameters of an in service MW. Then, two marginal distribution functions of MW′s remaining lifetime are obtained using the two degradation parameters respectively. After that, Copula function is adopted to describe the correlation between the two degradation parameters. The joint distribution function is then derived by fusing the two marginal distribution functions. Thus, a remaining lifetime prediction model is obtained. Finally, the Akaike information criterion(AIC) is used to select the best Copula function.