In order to analyze the distributing condition of urban passenger flow scientifically and correctly, the disaggregate Dogit model is presented to predict the public transportation share ration in city, which is carried out by means of analysis of the outer and inner factors that affect the choice of modes of transportation and is based on the random utility theory. Establishment of the model, parameter identification and the process of calculation are described in detail. Finally, according to the proposed algorithm, the public transportation share ratio forecast test is carried out using the field survey data. The results of independent sample test indicate that the model has a finer precision and stability.