Abstract: In this paper, the change law of LPG physical properties with temperature and pressure was solved by the Peng-Robinson equation. And the accuracy of the calculation model was verified by using the reference material of propane and n-pentane. The results showed that the model was reliable and accurate which could accord with engineering practice experience Antoine formula. Saturated vapor pressure of LPG increased geometric linearly as temperature went up. Liquid phase density decreased and gas phase density went up with temperature increasing. Saturated vapor pressure of LPG with constant liquid phase composition was equal at the same temperature. In the prescribed two-component standard material system, propane and n-pentane fitting equations were obtained: Y₁=-2.092 3E-5X+1.002 5, Y₂= 0.011 32e^{-X/2 256.62}+0.010 89(Y represented the mass fraction in the liquid phase, Xrepresented pressure).