This paper analyzes the characteristics of chamber pressure and noise measured during the ground firing tests of missile propulsion system. The propulsion system is a key component which allows the guided missile to reach the target, and ground firing tests are essential for the analysis of ballistic resistance performance. It is necessary to measure the chamber pressure of the combustion tube to analyze abnormal combustion during the test, and strong impact noise is generated when the propellant is ignited for firing of the propellant. In this test, pressure and noise are measured four times during the ground firing tests of two types of propulsion systems. As a result of checking the noise change with respect to the change of chamber pressure inside the combustion tube of the same propulsion system, it is determined that the maximum sound pressure level is decided by the maximum pressure at the beginning of combustion. By analyzing the tendency between the maximum pressure and maximum sound pressure at the beginning of combustion through linear fitting, it has been confirmed that the Pearson's R value is close to 1. In addition, through a comparative analysis of the sound pressure measured at the same distance as the maximum pressure inside the combustion tubes of different propulsion systems, it is found that the maximum sound pressure is relatively high depending on the diameter of the nozzle and the combustion gas diffusion angle, despite the low initial combustion pressure.