Abstract: Using the quasi-harmonic method,this paper anchored at the five stations in Yantian Port sea area of Sansha Bay for 27 hours in December,2015 for study of the tidal current characteristics.The harmonic coefficients of the O₁,K₁,M₂,S₂,M₄and MS₄ tidal current constituents were calculated for their north and east components.The tidal current elliptic factors were also computed.Meanwhile,the tidal type was analyzed.It was demonstrated that,the tidal and current type in Sansha Bay was regular semidiurnal tide,while the ratio of shallow water tidal current constituent to total current was very low.The ellipticity in absoluted value of M₂ tidal was less than 0.2.The tidal current mainly presented in N-S reciprocating movement.The magnitude of ebb was larger than that of flood.The maximum possible flow velocity was between 113 cm/s and 135 cm/s,greater at the deep station and smaller at the low station.The velocity decreased gradually from surface to bottom generally.The residual current was generally small,less than 8 cm/s usually and the minimum was about 2 cm/s in the observed area,performing fuzzy lay phenomenon and circulation structure.