Abstract: Taking tomato（Lycopersicon esculentum） seedlings as test materials, tissue culture was used, the effects of darkness treatment on the phenotype, growth index and expression of autophagy-related gene SlATG8f in tissue culture were studied, in order to provide reference for further study on the expression and regulation mechanism of autophagy-related genes under darkness stress.The results showed that the hypocotyls of tomato seedlings elongated significantly, the petioles elongated slowly, and the synthesis of chlorophyll decreased under dark condition.There was no significant effect on the root fresh weight of tomato seedlings, but the growth of shoot was inhibited.The decline of chlorophyll content was the most obvious manifestation of dark-induced senescence, and the autophagy-related gene SlATG8f had a significant response to the relatively early dark treatment during the 3-5 days dark treatment.