When facing the emerging circumstance that the Internet and business globalization have replaced the separation that was typical of the traditional business paradigm, especially the workflow and grid environment, challenges have been made to the traditional static access control model. To solve these challenges, we present a Dynamic Access Control Prediction mechanism for service workflow base on Markov chain. We abstract the service workflow in workflow and/or grid to an Ordered Service Sequence and through calculating the executable probability of service in OSS, we create an authorization policy based on the probability value dynamically. A simulation method of the mechanism is presented and practiced in ChinaGrid project.