Using 355 nm laser as excitation source,m-methylphenol multiphoton ionization and dissociation(MPID)was studied,m-methylphenol time-of-flight mass spectra of multiphoton ionization were obtained,There is no parent ion detected. The main possible dissociation and ionization channels were analysed. Using ab initio calculation to optimize the geometric structures of C₇H₈OH⁺ and C₇H₈OH at B3LYP/6-311++G(d,p)level,the stable structures are obtained. By exploring the potential energy surface of C₇H₈OH⁺,that the formation of C₇H₈OH⁺ is a reaction process without potential barrier is concluded.