A method and apparatus are disclosed for inferring a travel path in a public transportation system. The apparatus comprises: a single-line origin-destination (OD) inferring device configured to infer from boarding data of a bus line a passenger alighting stop on the line as an inferred passenger alighting stop according to historical data, wherein the boarding data comprises a passenger boarding stop during a predetermined time period and a number of boarding passengers at the stop. A transfer line inferring device is configured to infer a passenger transfer line as an inferred passenger transfer line according to the boarding data and the inferred passenger alighting stop obtained by the single-line OD inferring means.