This paper focus on single vehicle scheduling problem minimizing the line-side inventory of mixed-model assembly lines, considering the assembly sequence as an input.An exact algorithm is proposed based on three newly introduced concepts: conflicting, tight subset and complete conflicting subset, which divide the transportation operations into three classes.The solution generated by the algorithm is proved to be optimal. The algorithm is compared with the most popular FCFS (first-come, first-served) rule, and results shows the advantages of the algorithm, especially for large instances of the problem.