Abstract: Reasons that were not synchronized between multiple hanging chains of sheep slaughtering processing lines were analyzed.Advantages and disadvantages of a variety of synchronization methods were compared. Based on field bus technology，examples that frequency converters were controlled by PLC via digital communication using closed-loop speed control and position alignment control were introduced. System has advantages such as high reliability，practicability and operation simple.It was carried out in the project of‘Inner Mongolia Bamei sheep industry limited 120h sheep slaughter processing line equipment and supporting facilities’，and‘Inner Mongolia Xiaofeiyang food limited sheep slaughter processing line equipment and the supporting facilities’and‘Mengyang livestock limited class produced 3 000 sheep slaughter processing project’，and ideal effect was acquired.