Abstract: Complicated phase changes occur during the depletion exploitation of gas condensate reservoirs, which causes the precipitation of condensate oil and the mixed flow of gas phase and oil phase. Due to few research reports done so far, a new dimensionless deliverability equation of gas condensate reservoir is established by means of Taylor series expansion and polynomial regression on the basis of the inflow performance equation of gas condensate reservoir in pseudo-steady state in this study. Firstly, the definite integration of pseudo-pressure function in the equation is developed by Taylor series based on the inflow performance equation of gas condensate reservoir in pseudo-steady state; secondly, the coefficients of Taylor series are calculated by steady-state theory and polynomial regression method; finally, the dimensionless deliverability equation of gas condensate reservoir is established by analytic method. Its application shows that the inflow performance curve calculated by the dimensionless deliverability equation coincides with actual data of system well testing, which indicates that this equation can describe the two-phase inflow performance of gas condensate reservoir more accurately. Moreover, the open flow potential obtained by dimensionless deliverability equation is smaller than that by conventional dry gas conversion method; the open flow potential calculated by dimensionless deliverability equation which considers high velocity flow effect is much higher than the one that ignores the high velocity flow effect.