The invention relates to a SAGD (Steam Assisted Gravity Drainage) development and staged injection-production allocation method. The method comprises the following steps: 1) performing first staging and classification on all production wells in a production area according to a cumulative steam-oil ratio (cSOR); 2) counting the sum of the single-well remaining reserves in each stage as the basis offirst steam distribution, and calculating the steam distribution of each stage; 3) sequencing the single-well remaining reserves in each stage from large to small, and performing second staging and classification based on the single-well average remaining reserves of all wells in the production area; 4) calculating the steam distribution of each class; 5) sequencing from large to small accordingto subcool, performing third staging and classification according to subcool larger than 0 and subcool less than or equal to 0, namely, subdividing each class into two sub-classes, and calculating thesub-class steam distribution; 6) performing normalization processing on the cSOR of each sub-class, the single-well remaining reserves and the subcool; 7) introducing a comprehensive steam distribution factor, and calculating the comprehensive steam distribution factor percentage of each well in order to calculate the single-well steam distribution based on the comprehensive steam distribution factor percentage; 8) calculating single-well liquid production by utilizing single-well steam distribution according to a set production-injection ratio in the whole area.