Turnback capacity have become a major concern for the line capacity of rail transit. Take a rail transit stub-end terminal with four-tail tracks as background, based on N-track integrated model, a mixed integer programming optimization model is formed to estimate the turnback capacity and the track occupation strategies with the objective of minimizing occupation times of trains. Operations and design parameters such as tail track allocation strategies, train layover time, homogeneity of trains are also considered in this model. We illustrated our model using computational experiments drawn from the real rail transit line 16 in Shanghai and reached results which show that how the track occupation strategy, maximum layover time, homogeneity impact on turnback capacity.