In this study， we subjected Arabidopsis thaliana wild type and related transgenic lines to the concentration of 0, 50, 100, 200 and 400 μg/mL cefotaxime， investigated the effects of cefotaxime on the elongation of primary root, meristem activities, auxin distribution and transport and stem cell activities， explored the toxic mechanism of cefotaxime on the growth and development of primary root. The results showed that: (1) cefotaxime remarkably inhibited primary root growth of A. thaliana in a concentrationdependent manner. It also repressed the meristem size and the expression of CYCB1; 1， suggesting that cefotaxime can inhibit the meristem activities of root tips. (2) Cefotaxime reduced the expression of auxin reporter genes DR5∷GUS，DR5∷GFP and auxin polar transport proteins PIN1, PIN2, PIN3, PIN7 and AUX1， indicating that it can inhibit the auxin distribution and polar transport of root tips. (3) Cefotaxime downregulated the expression of quiescent center marker lines WOX5∷GFP, QC25 and QC46, as well as the expression of SHR and SCR proteins， indicating that it can inhibit the stem cell activity of root tips. Collectively, cefotaxime regulates the growth and development primary root in A. thaliana by repressing the auxin distribution and transport， stem cell activity and meristem activity.