This paper presents a method for thermodynamic calculation of the axial flow turbocharger turbine with variable geometry nozzle. With the quotation of three pulse coefficients, the fluctuating turbine is regarded as isobaric turbine. As the turbine flow passages are given and by means of the variable geometry nozzle, the matching between compressor and turbine can be satisfied. Taking advantage of the gas table and the practical losses, the reaction, the outlet flow angle and the throat area of nozzle can be calculated by means of iteration. As the entry pressure or temperature of gas is granted, the necessary entry temperature or pressure of gas can be obtained through iterating calculation, The equivalent area of turbine flow passages is evaluated. The calculations indicate that the iterating calculation is converged and the calculated throat area of nozzle accords with practicality.