Based on the property of cyclostationarity when fault arises in rolling bearing, The spectrum correlation (SC) or spectrum correlation density (SCD) based on second order cyclic statistic is improved and a new time-frequency analysis method naming improving spectrum correlation (ISC) is proposed. The improved method has the advantages of higher noise-resistant advantages over SC. It usually takes on modulation phenomenon when fault arises in rolling bearing, and the aim of fault diagnosis is to extract the fault characteristic frequency or cyclic modulation frequency only and neglect the modulated frequency or carrier frequency, so the ISC method is improved further and the integrated improving spectrum correlation (IISC) is proposed. The IISC extract the modulation frequency only which has the advantages of clearer expression effect and much better extraction effect. The above stated is verified through rolling bearing’s three fault types (inner race fault, outer race fault and ball fault).