Needle throttle valve (NTV) is a key equipment to ensure the safe production of shale gas fields, but it is often seriously eroded by the solid particles in the produced gas. At this work, the CFD-DEM coupling calculation method is adopted to investigate the internal flow field characteristics and the erosion rate of each component of the NTV under gas-solid two-phase flow. The accuracy of the numerical model is validated by the comparison results of simulation and experiment. The results show that with the increase of particle diameter, the maximum erosion rate of each part of the valve generally increases. When valve opening degree (VOD) is equal to 0.5, it has the best effect on suppressing erosion rates at high flow velocity. There is a “vulnerable zone” of the spool cone that is not affected by the changes in particle diameter and VOD, which occupies 2/3 of the height of the spool cone. This work not only predicts the vulnerable zone of each component of the valve, but also reveals the erosion mechanism of the NTV, and can provide a reference for the design and maintenance of the valve.