Enterovirus 71 (EV71), a member of Picornaviridae, causes severe neurological and systemic illness in children. To better understand the virus-host cell interactions, we performed a triple-SILAC-based quantitative proteomics study monitoring host cell proteome changes after EV71 infection. Based on the quantitative data for more than 4100 proteins, ~17% of the proteins were found as significantly changed (p<0.01) at either 8 or 20 hours post infection (h.p.i.). Five biological processes and seven protein classes showed significant differences. Functional screening of 9 regulated proteins discovered the regulatory role of CHCH2, a mitochondrial protein known as a transcriptional activator for cytochrome c oxidase (COX), in EV71 replication. Further studies showed that CHCH2 served as a negative regulator of innate immune responses.