  Shanghai Coherent Light Facility (SCLF) is a quasi-CW hard X-ray free
electron laser user facility which is recently proposed. Due to the high
repetition rate, high quality electron beams, it is straightforward to consider
an X-ray free electron laser oscillator (XFELO) operation for SCLF. The main
processes for XFELO design, and parameters optimization of the undulator, X-ray
cavity and electron beam are described. The first three-dimensional X-ray
crystal Bragg diffraction code, named BRIGHT is built, which collaborates
closely with GENESIS and OPC for numerical simulations of XFELO. The XFELO
performances of SCLF is investigated and optimized by theoretical analysis and
numerical simulation.
