Abstract: Gamma detection sensor and angle detector are adopted in the near-bit azimuth gamma MWD (measurement while drilling) system, which improve the accuracy of azimuth gamma MWD. The Gauss minimum frequency-shift keying modulation technology is adopted in the electromagnetic wave transmission system, which improves the formation interference resistance and attenuation resistance of communication signal, so that the stability of the instrument gets better. The integrated circuit technology is applied in the surface information processing system, which enhances the stability of circuit system. All functional modules of signal and information processing software are integrated highly to make the operation more convenient. The near-bit MWD system has the function of borehole lithological composition imaging, so it can reflect the lithological change characteristics of its drilling formations more directly and comprehensively, which is conducive to accurate geosteering. The field application indicates that the near-bit MWD system performs stably and its measurement data is accurate, so that the field geosteering technicians can carry out geosteering accurately in time by analyzing the shape of the near-bit azimuth gamma curve, so as to adjust the well trajectory in time. The application of the near-bit azimuth gamma MWD system greatly improves the reservoir drilling rates of drilled horizontal wells.