The invention discloses a method for judging the passenger traffic flow state of a urban rail transit section, which comprises the steps of calculating the interval passenger full-load rate of the interval passenger traffic flow state, and construct the time-series sample sequence of the state parameter, constructing a state parameter ordered sample sequence, and classifying the classification bythe optimal segmentation clustering method to ensure the classification to ensure the continuity of the sample and the continuity of the state; classify statistical periods with similar parameter samples into one category; proposing the division scheme of passenger traffic flow state in the target line interval, determining the segment passenger traffic state status category based on the parameterthreshold, accurately determining passenger traffic flow status. The decision-makers can timely and accurately grasp the passenger flow operation state and the passenger flow change law, and preparefor daily dispatch and work.