Abstract: This paper deeply studies the model of the Beggs-Brill liquid holdup, which is widely used in engineering design of the gas-liquid two-phase flow in pipeline. The problem existing in the model is pointed out when it is employed to calculate the liquid holdup of the inclined pipeline. Based on the mathematic tools, this paper deduces the critical conditions of this model and obtains the range of the angle of the inclined pipe. Also, a method which can be used to liquid holdup calculation of inclined pipeline is proposed in the paper. The calculation results of these two methods are compared with the experimental data. It shows that the relative error of the proposed model is less than the Beggs-Brill's.