The systems of diurnal tidal wave (K1) and semi-diurnal tidal wave (M2) in the Beibu Gulf are studied with numerical method. Also discussed in this paper are the influences of the Qiongzhou Strait, the bottom friction term, the horizontal turbulent friction term and the inertial (acceleration) term in dynamic equations on the tidal system. The calculated results show that there is an independent left-handed tidal system in the diurnal tidal wave of the gulf, the amphidromic point being roughly located at Taigeli Island; that the semi-diurnal wave constitutes no tidal system, generating a small tidal range in the region near Feizhulong Islands; and that the influence of the tidal wave from the strait on the tidal system of the K1 is not evident, but its effect on the system of the M2 component tide is quite obvious. The bottom friction term, the horizontal turbulent friction term, and the inertial term have effects upon the tidal system in the gulf.