ObjectiveTo investigate the fragmentation pathways of Chuan’agelei (a new drug) and its flatten structure ferulic acid and ligustrazine. MethodsChuan’agelei, ferulic acid and ligustrazine were subjected to analysis by ESI-MSn in negative mode. Their fragmentation pathways were explained using the Mass Frontier 6.0 software. We also compared the fragmentation mechanisms of Chuan’agelei, ferulic acid and ligustrazine, and the fragmentation pathways were analyzed systematically. ResultsIon peaks m/z 312 \[M-H\]-, 283, 268, 193, 178, 149 and 134 were observed for Chuan’agelei; m/z 178\[M-H\]-, 149 and 134 for ferulic acid; and m/z 135 \[M-H\]- for ligustrazine. ConclusionChuan’agelei is cracked mainly by losing -CH3, -COOH and tetramethyl pyrazine. Ferulic acid is cracked mainly by losing -CH3 and -COOH, while ligustrazine can not be cracked.