The energy extracted from ocean waves is one of the promising types of renewable energy to meet the energy demands. There are several projects conducted worldwide on various wave energy designs and one of them is floating oscillating water column (FOWC) type. The most investigated FOWC device currently is the backward bent duct buoy (BBDB) concept. However, the full potential of FOWC, is still not fully investigated and understood. Therefore, this paper presents an overview on most of the investigations previously conducted on FOWC. The optimised design parameter of FOWC in terms of main body corner shapes and buoyancy module shapes will be presented and suggested.