Abstract: Shanghai Synchrotron Radiation Facility (SSRF) is the 3rd advanced generation light source, so the beam stability is very important for experiment users. The fast obit feedback (FOFB) system can suppress obit noise within some bandwidth to a small range, which guarantees obit stability around extracted light. The SSRF FOFB system is a distributed fiber network with high speed and real-time feedback control, in which SVD algorithm was used to calculate generalized inverse matrix, and PI regulator was applied for parameters of corrector’s power supplies. The hardware was integrated with independent commercial modules, and the software was developed by SSRF based on EPICS and vxWorks platform. The SSRF FOFB system has satisfied designing requirements, and was run into operation in 2014 after several improvements. Presently, the orbit noise suppression bandwidth is up to 100 Hz, and the FOFB system beam stability could be below 0.1 μm （RMS）, which are the best level among the international 3rd generation light sources.