Abstract: To ensure the safety of drilling operations in the complex geological conditions of western South China Sea, reduce the risk of stuck or hindered downhole instruments during drilling, and meet the demand for reservoir porosity parameters in geological reservoirs. This paper introduces the basic structure of logging-while-drilling (LWD) nuclear magnetic resonance (NMR) logging instrument of Baker Hughes. Based on the experience of applying the LWD NMR tool in this region, it summarizes the precautions during the operation process and analyzes the quality control methods for LWD NMR logging data as well as the environmental impact factors and correction methods. Through a comparative analysis of the results of simultaneous measurements of LWD NMR logging with traditional neutron and density instruments on three wells, it was found that the relative error of porosity between them was 2.32%, which meets the standards of reserve evaluation specifications. The results indicate that it is feasible to replace neutron and density instruments with radioactive sources with LWD NMR logging instruments in the complex geological conditions of western South China Sea.