Studies on quantity discount have been in two directions since Buchanen published that suppliers provide quantity discount for price discrimination and for channel efficiency. The model on quantity discount for price discrimination has been researched in economics. On the contrary, the model on quantity discount for channel efficiency has been studied in production management with some assumptions and focuses different from economics. In this thesis, the differences in two areas are analyzed and a two-stage quantity discount model is suggested. This model integrates quantity discount models researched in each area. Also, purchasing situations for implementation of two-stage quantity discount model are specified. Finally, the discount rate required in each stage for implementation of this model is suggested under some conditions.