In order to study the effects of surrounding humidity on the constant-volume combustion characteristics of winding combustible cartridge case (CCC), the hygroscopic properties of winding CCC were studied by weighing method and the samples saturated in different humidity were tested by a closed-bomb test. The results show that the winding CCC has a better hygroscopic ability.The higher the relative humidity, the stronger the hygroscopic ability. When the relative humidity is 89.0%, the amount of absorption is about 2.89%.Under the condition of loading density of 0.20 g·cm^-3, with increasing the relative humidity, the burning rate of cartridge significantly reduces, and the combustion ending time extends from 2.40 ms to 3.30 ms, the maximum pressure decreases from 189.75 MPa to 174.32 MPa, the impetus decreases from 756.62 kJ·kg^-1 to 649.33 kJ·kg^-1 and the covolume increases from 1.01 L·kg^-1 to 1.30 L·kg^-1.