Regarding the wide application of geomagnetic field measurement in magnetic prospecting， navigation， and positioning， the measurement range of the single-cell self-oscillating optically pumped magnetometer （OPM） is limited by the phase-shift circuit， and the existing dual-cell OPM abroad exhibits a low integration degree and poor portability. In this study， the integration of the dual-cell OPM is improved to break the blockade and improve the research level of the domestic OPM. Through the derivation and demonstration of the principle of the OPM， a highly integrated structure design of the dual-cell cesium OPM is presented. A VCSEL is used as the pump light source， and a knife-edge right-angle prism mirror is used as the spectroscope， while other components are arranged symmetrically along the optical axis. A dual-pump light structure with left- and right-handed circularly polarized light and a dual-cell arrangement is used， which achieves precise phase-shift compensation and avoids the need for a phase-shift circuit. The geomagnetic field in the experimental environment is 37 586.79 nT， as measured by a prototype， and the magnitude of the triaxial component is obtained via the scanning method. The measurement range of the OPM prototype is 25 700-77 000 nT， and the sensitivity is approximately 20 pT$\sqrt[]{\mathrm{H}\mathrm{z}}$. The experimental results are consistent with the comparative measurement and theoretical calculation results， validating the theoretical analysis of the dual-cell OPM and confirming its feasibility， accuracy， and advantages for improving the system integration.