Background: Shanghai Synchrotron Radiation Facility (SSRF) is one of the third generation synchrotron radiation light sources in the world. Canted beamline which means two underlator are installed in one straight section is designed to increase the capacity of SSRF beamlines and thereof the interlock system for the canted beamline. Purpose: The aim of Canted beamline interlock system is to protect users and beamline components from the radiation of synchrotron light source

and ensure the Canted beamlines to run harmoniously. Methods: Based on Programmable Logic Controller (PLC)

Canted beamline interlock system puts forward beamline arbitrary signals and two searching paths to solve a series of difficulties such as the interlock relationships of shared components and shared hutch area. Results: In case of emergency

Canted beamline interlock system closes the photon shutters or requests the storage control system to abort the stored electron beam to assure personal and beamline device safety according to preset interlock logic. Conclusion: The designed Canted beamline interlock system collaborates smoothly with other control systems and works well from July 2013 till now. The design methods presented here provides reference for the following Canted beamlines in phase-II beamlines project in the near future. Abstract