The problem of minimizing the PCB assembly time for parallel multi-headed mounter is studied in this paper. Aim at the placement sequence problem with the assigned feeder, a new optimization algorithm is proposed based on scatter search (SS) algorithm. First, the scatter search approach and the machine's work model are presented. Second, the two improvement method SS1 and SS2 is discussed for the evaluation solutions. Furthermore, the create and combine method of reference set is proposed. Finally, experiment is performed to compare the performance between SS algorithm and Genetic Algorithm with 38 evaluation boards, and the results shows the efficiency of the proposed approach.