A series of resonant column tests were conducted on coral sand taken from the Nansha Islands, South China Sea with different grain gradations. The small-strain shear modulus G₀ of the coral sands with various void ratio e with the confining stress of 20~300 kPa was obtained. The influence of coefficients of uniformity C_u, mean particle size d₅₀, and fines content F_c on G₀ of coral sand was investigated, and the G₀ formulation for coral sand was established. For the constant effective confining pressure σ0', the curve of G₀-e moves downward as the increasing C_u, and moves upward as the increasing d₅₀. The G₀ firstly decreases and then increases as the increasing F_c, and the G₀ reaches the minimum value for F_c of about 20%. The G₀ prediction equations of terrigenous sandy and gravelly soils will obviously underestimate the G₀ value of coral sand. The influence of F_c on G₀ essentially results from the change of C_u and d₅₀ for coral sand with various F_c. The G₀ prediction equation of coral sand related to C_u and d₅₀, which implies the influence of F_c on G₀, was proposed, and the correction factor A' related to the morphology and mineralogy of the particle form of coral sands was incorporated in the proposed G₀ prediction equation. The validity of the G₀ prediction equation was verified by comparing the measured and predicted G₀ values of coral sands from different seas.