According to the lab data on groundwater samples during two tidal cycles from monitoring wells J1 and J2 along eastern coast of Leizhou Peninsular, the paper analyzed the anion Br-'s concentration, variation and relationship with other main ions. The results demonstrate that Br- comes mainly from seawater intrusion, and the basic types of measured well are Na+K·Ca·Mg－Cl·SO4, and the types of J2 is Na+K·Ca·Mg－Cl·SO4·HCO3;the average content of Br- in J1 is 11.69~14.35 mg/L and the concentration of Br- in J2 is almost half in J1's. Br- statistical characteristics every well change with the number of measurement. Combined with the ratio of Br-/Cl- and the invironment of measured well,it is thought that J1 primarily has sea-phase and J2 has river-sea phase in term of Br-/Cl-; Br- owns almost the same relative amplitudes with Cl- and SO42-,which show Br- also actively takes part in the process of seawater intrusion; the correlation of Br- with other ions also varies with wells and the ratio of Br- to Na+ is the lowest among the ratio of Br- to cations. the highest is K+; the ratio of Br- to Mg2+ is in the meantime. The frequency in the region of milligram equivalent ratio chiefly appears the distribution forms of left lean, sharp peak and flat peak, especially in well J2, the ratio of γBr-/γK+ is close to normal. The relativity of milligram equivalent ratio and mass equivalent ratio is consistent. The linear relationship between Br-/Na+ and Br-/Cl- is good. The paper finally made linear LST fitness.