Abstract: The hydroxymethyl substituted coumarin comounds are the homonuclear compounds of Armillarisin A. Since Armillarisin Ahas a cure effect on acute bile duct cholangitis, it is of value to medicine and chemistry area. Now, not only the Armillarisin Ahas been synthesized, but also a great deal of research work attemptting to improve the cure effect by changing substituted group of the compounds has been done.We worked for finding mass spectral fragmentation rule of these compounds, which were synthesized by Department of Chemistry of Nanjing University. The results are shown in the table. The mechanism of the fragmentation of hydroxy-metyl substituted coumarin is discussed in the paper too.