Abstract: The joint ground and underground gas extraction mode has gradually become one of the important technologies to prevent coal gas disasters and realize the safe and efficient coordinated development of coal and gas resources in high-gas mining areas. The monitoring data show that during the mining stage of the working face, underground boreholes, surface vertical wells and L-shaped horizontal wells all played positive roles to varying degrees. Compare with surface vertical wells, L-shaped wells and underground boreholes have longer gas extraction durations and more stable gas extraction volumes. To study the influence mechanism of the evolution of the stress field and fracture field of the overburden rock during mining on the joint ground and underground gas extraction, a geomechanical model considering the mining of the working face is established. The time-space evolution laws of the displacement field, stress field and fracture field of coal and rock masses during the mining process of the working face are analyzed. The correlation between the stress variation of the overburden rock and the gas extraction of L-shaped horizontal wells is revealed. Studies show that no gas is detected in L-shaped wells during the period when the vertical stress peak occurs in the nearby surrounding rock, but rather after the stress gradient reaches the peak and before it tends to stabilize. This is related to the rapid evolution of the fracture zone after the overburden stress caused by the mining of the working face reaches its peak. The sharp decrease in rock layer stress until it stabilizes marks the full development of the fracture zone, which is a necessary condition for the formation of stable gas flow during gas extraction from the L-shaped well at this location. During the mining process of the working face, the vertical stress of the overburden rock of the coal seam undergoes two variation intervals: a rapid decrease after gradually reaching the peak and a slow decrease to a stable state. The dividing point is the turning point where the stress. When the stress change turning point occurs at the B target point of the L-shaped well, gas is detected in the L-shaped well. The L-shaped well stably played the role of extracting gas from the working face and became an important part of the joint ground and underground gas extraction mode. Studies show that the stress variation curve of the mining rock mass can be referred to for the layer optimization and well type design of L-shaped wells.