Acetonitrile (CH₃CN) has been widely employed as biomass burning tracer. However, the current application of CH₃CN absolute mixing ratio as the thresholds may misidentify biomass burning due to the interference from other CH₃CN sources in anthropogenic‐influenced environments. High levels of CH₃CN were observed with minor biomass burning impact but still followed a similar correlation with carbon monoxide (CO), suggesting their shared source, most likely, vehicular emission. By analyzing the available literature including more than 30 worldwide field measurements, the enhancement ratios (EnRs) of CH₃CN to CO for biomass burning were found as 2.01 ± 0.16 ppbv/ppmv, well distinguished from the EnRs obtained in urban measurement (0.26 ± 0.04 ppbv/ppmv). An example is given and the application of EnR to identify biomass burning is discussed. The results suggest that the correlation between CH₃CN and CO and their EnRs can be used as more specific indicators for biomass burning.