Abstract: In response to the problem of the size of the narrow coal pillar in the goaf excavation roadway of the 14E02 inclined thick coal seam in Shajihai Coal Mine, theoretical analysis, numerical simulation, and mine pressure measurement methods are used to determine the reasonable width of the narrow coal pillars. The research results show that based on the theory of internal and external stress field theory, the width of the narrow coal pillars in the goaf excavation roadway should not exceed 6.42 m（upper limit）, and based on the elastic-plastic limit equilibrium theory, the width of the narrow coal pillars should not be less than 3.96 m（lower limit）. The numerical simulation results of goaf excavation roadway indicate that the 4-5 m coal pillars can be stable during excavation, but they lose their bearing capacity during the recovery period and are prone to joint damage between the roadway and the coal pillars, making roadway maintenance extremely difficult. When the width of the coal pillar is≥6 m, the narrow coal pillar can form a stable elastic core during excavation and mining, which is more conducive to roadway maintenance. The reasonable width of the narrow coal pillars is recommended to be 6 m, which is basically consistent with the upper limit value of the narrow coal pillars width（6.42 m） calculated by the internal and external stress field theory. It is more reasonable to use the theory of internal and external stress field theory to determine the width of the narrow coal pillars in the fully mechanized caving face of inclined thick coal seams like Shajihai Coal Mine. Corresponding rock control measures and support schemes have been proposed for the failure characteristics of narrow coal pillars in goaf roadway of fully mechanized caving face in inclined thick coal seam.