To investigate the key factors which influence the erosion of propellants and the relationship between erosion and each factor, eight triple base gun propellants were produced. The amounts of erosion were determined with semi-closed bomb experiment. The relationship was found between the erosion of propellants and these factors, through contrasting and analysing explosion heat, explosion temperature and gases composition of these propellants respectively. Results show that explosion temperature is the key factor influencing the erosion of propellant, and there is a linear relation between erosion rate and explosion temperature(3100~3700 K), which increases obviously with the rise of explosion temperature. Explosion heat has not obvious influence on erosion, but erosion time or pressure impulse palys a more important role. H₂O is the most influential constituent to propellant erosion coefficient in five propellant combustion products, and the relationship between these products and propellant erosion is complex, now it is difficult to have a quantitative description separately.