Disclosed is a system for sensing a UF6 gas leak in a nuclear fuel manufacturing process. The system is configured to sense whether or not there is a UF6 gas leak by optically detecting UO2F2 in a solid state generated due to a reaction with outside air. This allows prevention of damage to a detection apparatus by means of sensing in a non-contact manner whether or not there is a UF6 gas leak. Further, the system extends the mechanical life of and reduces the maintenance and repair costs for the detection apparatus.