The floating seedlings of "Honghua Dajinyuan" were used to study the effects of ciprofloxacin（CIP） and oxytetracycline（OTC） on the growth of flue-cured tobacco.Analyzed the growth status，the changes of chloroplast structure and the content of pigment，the changes of photosynthetic index and the accumulation of antibiotics in flue-cured tobacco seedlings under the concentrations of antibiotics including 0 mg/L，5 mg/L，15 mg/L，30 mg/L，45 mg/L，and 60 mg/L were analyzed.The results showed that low concentration of antibiotics（CIP<15 mg/L and OTC<5 mg/L） stimulated the growth of flue-cured tobacco seedlings，while high concentration inhibited the growth of flue-cured tobacco seedlings.Both antibiotics at low concentrations damaged the chloroplast structure of flue-cured tobacco leaves under transmission electron microscopy（TEM） observation.As the concentration of two antibiotics increased，the content of chlorophyll，the net photosynthetic rate（P_n），transpiration rate（T_r），and stomatal conductance（G_s） in the leaves of flue-cured tobacco seedlings gradually decreased，while the intercellular CO₂ concentration（C_i） increased gradually with the increase of the concentration of the two antibiotics.The accumulation of CIP and OTC in different parts of flue-cured tobacco seedlings decreased in a pattern of root > leaf >stem.It is indicated that low concentration antibiotics can promote the growth of flue-cured tobacco seedlings.Antibiotics damage the chloroplast structure of leaves，resulting in a decrease in the content of pigment and the photosynthetic capacity，ultimately affecting the growth and quality of flue-cured tobacco.Therefore，the use of antibiotics should be reduced in production to avoid potentially increased risks of plant enrichment.