Abstract: In order to find out the suitable cultivation practices for Yunyan 97 in Zhaotong, Yunnan, the effects of planting spacing, nitrogen application rate and tip leaf length after topping on the agronomic characters of and chemical components in upper and middle leaves of Yunyan 97 were studied with L₉(3⁴)orthogonal experiments. The results showed that:1) There existed extremely significant difference in plant height, significant difference in stalk circumference, internode length, number of effective leaves, cutter length, length and width of tips, and no significant difference in cutter width and the length and width of flying between treatments. 2) Within 15 days after topping, the length and width of the 1st and 3rd leaves from top showed a trend of growth, the trend flatted afterwards. 3) The greatest increase of length and width of the 3rd leaf were up to 16.2 and 4.9 cm, respectively, when the plants were set 50 cm apart, and in rows 120 cm apart, N application rate at 75 kg/ha and tip leaf length after topping 20 cm± 5 cm. 4) The chemical components in leaves was of better harmony for spacing 60 cm×100 cm, N application rate 60 kg/ha, tip leaf length after topping 30±5 cm. 5) At the planting density of 16665 plants/ha, spacing 50 cm×120 cm or 60 cm×100 cm, N 75 kg/ha and tip leaf length after topping 20±5 cm or 30±5 cm were more suitable for Yunyan 97.