Abstract: The relation of distribution, density and diurnal changes of stomatal opening and closure in six plants of alpine Kobresia humilis meadow were studied during May–September in 1986. The results indicate that the leaf stomata of most plants are distributed in both the upper and lower epidermis, but with the K. humilis they are distributed in the lower epidermis, and with the Festuca ovina, they are all distributed in the upper epidermis. The leaf stomata open at 9 am until 3pm and then close gradually. Transpiration intensity of plants varies with the stomata’s opening and closure. The transpiration intensity of K. humilis achieved peak at about 11 am, but Elymus nutans and Saussurea superba at about 1 pm, after which it falls gradually until stops completely sunset. The changes of stomatal opening and closure as well as the transpiration intensity of plants are affected by both air temperture and the relative ambient humidity.