An acoustic pressure amplifier (APA) is capable of improving the match between a thermoacoustic engine and a load by elevating pressure ratio and acoustic power output. A standing-wave thermoacoustic engine driving a resistanceand-compliance (RC) load through an APA was simulated with linear thermoacoustics to study the impact of load impedance on the performance of the thermoacoustic system. Based on the simulation results, analysis focuses on the distribution of pressure amplitude and velocity amplitude in APA with an RC load of diverse acoustic resistances and compliance impedances. Variation of operating parameters, including pressure ratio, acoustic power, hot end temperature of stack, etc., versus impedance of the RC load is presented and analyzed according to the abovementioned distribution. A verifying experiment has been performed, which indicates that the simulation can roughly predict the system operation in the fundamental-frequency mode.