The influence of trip distance distribution of passengers on the competitiveness of long bus lines was explored, from the perspective of continuous expansion of urban construction land. A calculation method to describe the choice probability of a bus stop was presented and a passenger flow assignment model based on Logit-SUE applied in the competitive public transit network was established. Then the influences of average passenger trip distance and residence dispersion coefficient on the choice probabilities of the bus line and the bus stops were explored. Results showed that average passenger trip distance had the trend of increasing with the continuous expansion of the city, and the competitiveness of long through-type bus lines decreased gradually since the urban rail transit was more suitable for long distance trips than the bus transit. The choice probability of each bus stop decreased as average passenger trip distance increased. The choice probabilities of the bus stops located in the center area of the line were less sensitive to the change of average passenger trip distance compared with that in the marginal area of the line. The expansion of the city led to the decrease of residence dispersion coefficient, and the competitiveness of long through-type bus line decreased accordingly. The choice probabilities of the bus stops decrease gradually with the distribution of passengers' residential locations changes from " small and scattered” to " large and concentrated”.