In order to calculate numerically the coefficient of performance and carry out analogue computation on ammonia-water absorption refrigeration cycle,it is necessary to seek out a lot of precise equations that can be used to calculate the density of ammonia-water solutions.The density of saturated liquid of ammonia and water was calculated adopting four types of equations by the help of Matlab 7.0 software.Due to polar material properties about ammonia and water,it is difficult to find an accurate equation used to calculate the density.With regard to ammonia saturated liquid density,the result of Rackett equation improved by Campbell is the most precise at the temperature range from -30 ℃ to 55 ℃ with the overall average relative error of 0.38% and maximum relative error of 0.41%.Concerning water saturated liquid density,the performance of Rackett equation improved by Campbell is the best at the temperature range from 6 ℃ to 100 ℃ with the overall average relative error of 0.58% and maximum relative error of 1.01%.The Yen Woods correlation is also an excellent equation.The overall average relative error and maximum error about ammonia is 0.73% and 1.32% respectively.With respect to water,the overall average relative error and maximum error is 1.38% and 3.59%,respectively.According to the mix rule and above quota rule of solution properties,a formula was presented to calculate the density of ammonia-water solutions.Two experimentation methods were introduced,and the experimental formulas can be used to test the accuracy of the theoretical formulas.The conclusions can be applied to calculate the efficiency of ammonia-water absorption refrigeration cycle.