EM challenge has became more and more critical with technology nodes shrinking, particularly for FinFET design with self-heating effect. Generally we could sign-off the IP/SOC handily by industry EM tool, but for standard cells itself, which usually has wide range of combinations of input slew/Output Load/Frequency/Toggle-rate in the SOC, and EM will limit its maximum Frequency and Drive-strength. In this paper, we provide an approach to do thermal-awared EM check and .Iib characterization for all std cell libraries, and a practice to do cell EM sign-off analysis and ECO in STA/ECO environment with this EM-awared .lib.