A business process is a logically related set of business tasks. Each task contains multiple activities, and each activity has its corresponding performers. To improve the efficiency of processes, some scheduling operations will be conducted between performers, thus causing the phenomenon of task preemption. In view of this phenomenon, a Logical Time Petri net (LTPN) is proposed to describe task preemption in concurrent business process systems. By classifying place and transition sets, the relationship between activities and performers are modeled, and then the assignment and triggering of tasks are realized. Note that we consider both the priority of the control place and time constraints, which better describe the task preemption process in business flow. In addition, we propose a novel scheduling algorithm for the task preemption model. Effectiveness and applicability of the proposed methods are verified by a case study.