This study aims to establish the residue analysis method of atrazine on soil and CaCl₂ aq by UPLC-MS/MS in order to provide theoretical basis and technical means for the detection and adsorption of atrazine in soil. The samples were extracted with acetonitrile and purified with C18 powder by QuEChERS technology, they were separated on the Acquity UPLC®BEH C18 column, gradient eluted with acetonitrile and 0.2% formic acid, then detected by UPLC-MS/MS and quantified by external standard method. Atrazine showed a good linear relationship in the range of 0.001-5.0 mg/L（r＞0.99）. At addition levels of 0.05-0.50 mg/kg, the recoveries of atrazine in soil and 0.01 mol/L CaCl₂ aq were in the range of 80.9%-115.4% with relative standard deviations of 1.5%-3.5%.The limit of quantifications（LOQ） were 0.15 μg/kg and 0.08 μg/kg The method is simple, high sensitivity, fast and accurate,which is suitable for the determination of atrazine in soil and CaCl₂ aq.