This paper first introduces the imperial kiln site unearthed gourd shape in early Ming dynasty, and middle-late mantou kiln, clarify imperial kiln from using gourd shape, change to the use of steamed bread inevitability of kiln. Combined with signs and unearthed documents, think jintong steamed bun shape to the wanli period of the imperial kiln kiln are narrow after wide type, before after mid wanli into such as wide, before and after the change is in the process of in situ by preheater kiln head advancing continuously. Also calculated: Ming guan kiln 20; Xuande period has a kiln 58, including dragon cylinder kiln 32, six green kiln, kiln, 20 熿 kiln, mid jintong, will be transformed into 16 cylinder big dragon kiln green kiln; Jiajing and wanli period with dragons cylinder 16 big kiln, 熿 kiln and kiln 20 of color, green kiln 44. In addition, the division also has carried on the textual research of kiln, think is 熿 kiln drying of low-temperature glaze kiln burning, rather than in the past that color baking furnace; Color the high temperature color glaze kiln kiln is firing, rather than previously thought is prime of low-temperature glaze color; Wind fire is the fire of kiln kiln, rather than ever think of is the floorboard of the kiln.