Automatic model checking is used to determine the error-free design of the SIS (Safety Instrumented System) and to find the logical errors in the chemical processes. It proposes an automatic technique to provide and to modify the P&ID design of SIS control logics. This method can be applied to verify its correctness of SIS and to find the logical errors by synthesizing a feasible sequence automatically. This study focuses on automatic verifying and synthesizing for the design, operability and reachability of SIS control logics in chemical processes. (C) 2009 Elsevier Ltd. All rights reserved.