Shanghai Deep Ultraviolet Free Electron Laser(SDUV-FEL) test facility is an integrated multi-purpose test bed for FEL principles.In this paper
we focus on the development of an interlock system for SDUV-FEL vacuum protection.Hardware and software of the system implementations are introduced.A distributed control system composed of a PLC
an embedded computer and consoles based on EPICS toolkit is described in details.The system has been used for cascaded HGHG FEL experiment.Stability and reliability has been demonstrated.