Abstract: The experiment was conducted to study the effect of the fertilizing biogas slurry once and separately on physiological character, quality and yield of celery in order to provide a basis for application of biogas slurry on celery .The experiment with completely randomized design analyzed catalase activity, the content of chlorophyll, VC, reducing sugar and nitrate. The result showed: The effect in once or separately fertilizing biogas slurry and on photosynthetic physiological indexes, quality and dry matter content in celery is studied. The experiments with design method of complete random were conducted to study. The result is as following: Either once or separately fertilizing biogas slurry, Photosynthesis physiological index and quality of celery were obviously increased, the dry matter content of celery was decreased, moreover there was no significant difference in dry matter content of celery. The contents of chlorophyll and the catalase activity of celery were increased 19.06%, 6.52% in the once top-dressing treatment with 300ml biogas slurry (A1I) than that applied chemical fertilizer (A1I). The contents of VC and the reducing sugar of celery were increased 9.07% and 51.31% in the once top-dressing treatment with 900ml biogas slurry (A2I) than that applied chemical fertilizer (B2I) while the content of nitrate was decreased 31.65%.There was no significant difference in quality and yield of celery between the fertilizing biogas slurry once and separately. The separately fertilizing chemical fertilizer treatment significantly reduced the content of nitrate in comparison with once fertilizing.