Currently, bus arrival time prediction studies have not yielded the best results under complex road conditions. A bus arrival time prediction mechanism based on the similarity of road conditions is proposed in this paper. By analyzing the past trip records of the bus, the historical traffic condition of each road section was estimated. The road condition for each trip records was extracted. In the operational phase, each road section’s traffic condition was estimated by gathering bus locations continually. The mechanism predicted bus arrival time for the rest bus station by the most similar historical which was searched by the time, distance, and real-time road conditions. The evaluation result using historical data of real bus trips shows that the arrival time prediction of the mechanism is accurate—with an absolute percentage error around 5%.