The feature of supporting dynamic change is required in the application of workflow management system.While some relational research fell short in terms of expressive capacity and algorithm complexity.Based on synchronization net

a formal workflow model

this paper proposes a definition of process change from logic and semantic view

then classifies elementary change units

and discusses the correctness of change.A whole process change in need is considered as a sequence of those change units.Therefore the complex problem becomes easy and the correctness of change is preserved strictly.Following the description of change

a new method to manage process change is proposed

so as to resolve the migration problem of on-the-fly process instance

centered on synchronizer.