Study on combustion instability in low-temperature ground test of a solid rocket motor was carried out in the paper. Based on FFT analysis of experimental data, this combustion instability phenomenon was attributed to acoustic instability. According to discussion of suppression methods of combustion instability and related engineering experiences, pertinent measures including adjusting content and particle size of stabilizer and increasing working pressure of the second stage properly were applied. With these measures, the combustion instability phenomenon in low-temperature ground test was eliminated, indicating that the adopted methods are effective. Main works of this paper could be taken as references for engineering development of the same kind of solid rocket motors.