Abstract: An automatic boiling temperature control system for the measurement of both isothermal and isobaric vapor liquid equilibrium data.(T-P-x-y)by dynamic method is presented in this paper, along with the principle of temperature control and total pressure measurement. The absolute pressure control in isobaric VLE measurement can reach the precision of ± 0.02mmHg, and in isothermal VLE data measurement, the precision of the constant temperature control is within ± 0.002℃. The total pressure P is determined by using an ebul-liometer to measure the boiling point of pure water which is then converted to the total pressure. The schematic diagram of the system and the experimental procedure are given in detail. Using this automatic control system, isothermal VLE data of methanol (1)-1,2-dichloroethane (2) at 50.00℃ and 60.00℃ were measured, and both of the data sets passed the point-to-point thermodynamic consistency test. The system has the advantages of accuracy, simplicity and rapidity in isothermal VLE data measurement, and in general, a data point can be determined in about 5 to 10 minutes.