To explore and validate the feasibility of in vivo real-time monitoring for brain tissue properties in stereotaxic radio frequency (RF) neurosurgery by near infrared spectrum technique, the change of absorption coefficient (μa and reduced scattering coefficient (μ's) of brain tissue is measured real-time by minimal invasive near infrared spectrum system in RF lesion of thalamotomy. The result indicates that absorption coefficient and reduced scattering coefficient increased when RF heating temperature was kept at 44℃, and μa and μ's decreased slowly when RF lesion was stopped, and the value of μa and μ's was a litter higher corresponding to the original value at the balance level. μa and μ's kept in the high level when the RF lesion temperature was set in 70℃. The μa and μ's real-time and in vivo monitoring for brain tissue by near infrared spectrum in stereotaxic RF neurosurgery is feasible.