Abstract: In the process of drainage and production of casing fractured L-type horizontal Wells, sand, coal particles and pulverized coal in the reservoir will lead to the blockage of effective gas production channels. In order to improve the effect of well cleaning, the conventional nitrogen foam well cleaning technology was optimized through theoretical calculation, parameter optimization and technological equipment optimization. The rotating coal breaking tip and pipe string pressure device can expand the particle size range of the wellbore blockage, reduce the risk of pipe string clogging, and solve the problem of pipe string supporting pressure in the process of well cleaning. In this study, a nitrogen foam regulator based on nitrogen foam density monitoring is designed to control the quality of nitrogen foam, which can realize real-time control of nitrogen foam quality. The optimized nitrogen foam cleaning process resulted in a 9.2% reduction in wash fluid loss, a 100% increase in sand carrying capacity, a 35.6% increase in wash completion (wash footage/horizontal footage), and an increase in wash efficiency from 53% to more than 84%. The research results have guiding significance for the operation of coal bed methane horizontal well sand clearing and plugging removal. The gas production capacity and drainage continuity of L-casing fractured horizontal Wells in Fanzhuang-Zhengzhuang block of Qinshui Basin have been improved by using this process to clean the wellbore.