A combustible cartridge is made of nitrocellulose, wood fibers and resin. It is easy to absorb moisture in a high-humidity environment and the NC-based materials may self-ignite after storage at higher temperature for a long time. A large number of studies have been carried out to improve the surface protection performance of combustible cartridges usually using a general nitrocellulose varnish. But the heat-resistance of the nitrocellulose varnish coating is poor. In this article, we develop a composite coating that improves the heat-resistance and salt wet resistance of combustible cartridges. The new composite coating was prepared by adding BN/silane composite particles and non-ionic surface active reagent Tween 80 into the nitrocellulose varnish by an optimized composition. The high temperature resistant performance and salt tolerance properties effect of the new composite coating for combustible cartridge were investigated by thermogravimetric experiment, muffle furnace experiment and salt wet resistance test. Compared with the control sample, the coated sample by the new composite coating was able to stand for 138 s at a high temperature of 220 degrees C, increasing the high temperature resistance time by a maximum percentage of 50 %. In a high-salt environment, the final water absorption percentage was only 0.2944 % when the coated sample is immersed in a high salt content water at 26 degrees C for three days, increasing the salt wet resistance by a maximum percentage of 70 %. Results show that the new coating using BN/silane composite particle can improve the high temperature resistant performance and salt tolerance properties of combustible cartridges effectively.