In this article, the method of the constant volume burner was used to measure the solid propellant burning rate under high pressure. The burning rate formula and the heat loss rate equation of the constant volume burner method were derived, and the effects of four factors (pressure increasing rate, burning time, ignition, and burning rate) on the heat loss of the constant volume burner during operation were carried out. Furthermore, the testing reproducibility on burning rate was analyzed. It was shown that sample size precision, moles per unit mass of propellant, and heat loss were the main factors for the accuracy of the constant volume burner method. The shorter the burning time, the faster the pressure increasing rate and the burning rate; the less the heat loss, the appropriate ignition way was to reduce heat loss ignition. Moreover, for both various burning rates of propellants, the parallel error of the test results obtained by the method was low, and the reproducibility was high. The burning rates measured by such a method showed a strong correlation to the burning rate.