Abstract: This research attempts to solve the surface localization of the principle sulcus on the lateral aspect of monkeys cerebral hemisphere.Based upon certains surface marks on the cranium,with the assistance of sliding calipers and stereotaxis instrument of type SN-2 № 800-3 (NARISHIGE)the measurtment had been made on 30 specimens (♂9,♀21) of cranium and brain of 3-6 years old Macaca mulatta of Guangxi fixed in 10% formalin beyond 3 months.By statistical analysis the formulae which have been made according to the relationship between the maximum cranial length,auricular height and minimum frontal breath with the position of the superior and inferior end of the sulcus centeralis and posterior end of the sulcus princinpalis have been presented.The ways which define the hind-limb area of Sm 1 and SS 11,the Ⅴ.1 area,the posterior part of middle and inferior frontal gyrus have been discussed.