Abstract: This study aimed to investigate the sunless grade index of tomato’s seedling stage and mature stage in solar greenhouse. According sunless experiments on tomato’s seedling stage and mature stage in solar greenhouse, meteorological grade indexes of chilling damage were explored in this study. The sunless damage was divided into 4 grades, which were non-damage, light-damage, medium-damage, and heavy-damage. The photosynthetic rates of plant samples and contrast samples were observed and analyzed by different durations of sunless. With the records of plants growing condition and analysis of sample yield after sunless treatment, the sunless grade indexes in solar greenhouse were decided. Results showed that the sunless grade indexes of seedling stage were non-damage (3 days and less than 3 days), light-damage (4-7 days), medium-damage (8-10 days), and heavy-damage (more than 10 days); the sunless grade index of mature stage: non-damage (3 days and less than 3 days), light-damage (4-5 days), medium-damage (5-10 days), and heavy-damage (more than 10 days). These results will provide the basis for sunless forewarning in tomato production in solar greenhouse.