An axial cyclone separator with a spindle vane has the advantages of low pressure drop and high collection efficiency. Collection efficiency is an important parameter for assessing the performance of a cyclone separator. Previous studies have shown that as the number of turns of a spindle vane increases or the pitch of the spindle vane decreases, the collection efficiency of the axial cyclone separator increases. There are two models for predicting the collection efficiency of an axial flow cyclone. One model by Hsiao et al. (2011) can predict the collection efficiency if the primary dimensions and inlet flow conditions of the cyclone are given. But the other model by Hsu et al. (2005) additionally requires a fitting constant to determine the collection efficiency. Because the accuracy of the model of Hsu et al. (2005) is limited by the fitting constant, it is necessary to find a fitting constant systematically. In the present study, we developed a method to determine the fitting constant for the model of Hsu et al. (2005) through experimental, numerical, and analytical investigation. It was found that the fitting constant is the function of flow transit time in the vane section. Finally, we compared the two existing prediction models with each other. Both model predictions agreed well with the experimental data.