Abstract: To explore the screening concentration of hygromycin B suitable for Arabidopsis thaliana seeds on 1/2 MS medium, seeds of Arabidopsis thaliana were sowed on 1/2 MS medium with various concentrations of hygromycin B（0, 20, 30, 40, 50 mg/L） after the sterilization of wild Arabidopsis thaliana, which were recorded M₀, M₁, M₂, M₃, M₄, respectively. Effects of hygromycin B on seed germination and seedling morphological changes were observed. Seed germination rate, seed germination potential in the 3 rd day, seedling leaf depigmentation and death rates in the 13 th day were investigated. In the 7 th day, seedling fresh weights, dry weights, relative water contents, taproot length were detected. The order of 5 hygromycin B levels efficiencies was given with variation coefficient-entropy weight-TOPSIS method by converse thinking. The results showed that hygromycin significantly inhibited seed germination and seedling growth of Arabidopsis thaliana. Through variation coefficient-entropy weight-TOPSIS method, inhibition effect order of different hygromycin B concentration solutions to Arabidopsis thaliana was as follow, M₄＞M₃＞M₂＞M₁＞M₀. The relative closeness of M₂ was 0.531 5, which was about 0.5 and the closest to 50% inhibitory effect. Conclusions as a result, 30 mg/L was used as the optimal hygromycin concentration for Arabidopsis thaliana screening in 1/2 MS medium, suitable for seedling transplanting during 7 or 10 days after seed sowing.