The paper is intended to analyze the correlation of traffic performance index and bus performance index, for which time series analysis of econometrics is used. Granger causality test, co-integration test, vector auto-regression model, and vector error correction model are employed to investigate the relationships between the two indexes in the short run and the long run. The results indicate that there exists a Granger causality between traffic performance index and bus performance index. The two indexes are correlated in the short run while they are not significantly correlated in the long run. The two indexes remain relatively independent as short-run co-movement effect dissipates.