Abstract: A link-to-link transition sampling method utilizing the historic data of link-to-link transition probability to obtain the multiple optimal routes between the given origin and destination in a road network (method of link-to-link transition probability for multiple optimal routes) was proposed to avoid the need of calculating the link travel times. Firstly, the link-to-link transition probabilities were calculated with travel data of time and region division. The impacts of traffic conditions were taken into account according to time division. And the problems of the large number of starting points and ending points and the insufficient data of specific point pairs in the road network were avoided by replacing the given starting point and ending point with the traffic zone. And multiple optimal routes were calculated with route sampling based on the link-to-link transition probability. The proposed method demonstrated the advantages of no need to calculate the link travel time, low requirement of data and easy implementation. A case study showed that the optimal routes obtained with the proposed method are much in accordance with the actual optimal routes. The size of traffic zones has minor impacts on the results, and the division of periods can effectively reflect the traffic conditions.