Abstract: Aiming at the technical problems existing in coal seam gas pressure measurement via directional long boreholes, a remote in-situ measurement system was developed. To ensure its stability, reliability and measurement accuracy, a full-factor integration method was proposed to guide the improvement and optimization of the system. The engineering feasibility and practical effectiveness of the system were verified through experimental research, and the faults occurring during system operation were identified simultaneously. On this basis, according to the analysis of system operation mechanism and failure paths, a conceptual model of system reliability was constructed. Furthermore, a mathematical model of system reliability was established by integrating the dynamic fault tree method, failure free operating period (FFOP) prediction method and cost-reliability allocation method. The results show that: the remote in-situ measurement system can shorten the pressure measurement cycle, but the influencing factors of system reliability are complex, the primary factor is the reliability of the measurement device, while other factors include drilling rig reliability, measurement field variations and technological processes; other influencing factors exert their effects on system reliability through the measurement device, thus, ensuring the tightness and pressure stabilization capability of the measurement device constitutes the key technical node for improving system reliability; the conceptual model of system reliability established based on dynamic fault gates clarifies the structural relationships among components and demonstrates the fault modes of the system; the mathematical reliability model constructed in the form of parameters realizes the quantitative analysis of the dynamic fault tree and mean time between failures (MTBF) prediction method; the reliability allocation based on calculation results balances the reliability of the overall system and its components, providing an optimization scheme for the continuous improvement of the system; taking the remote in-situ coal seam gas pressure measurement system as the research object, the full-factor integration method establishes a reliability research system covering the entire measurement cycle for different levels of the system.