Abstract: Plateau pika (Ochotona curzoniae) is one of the important pest rodents in the Qinghai-Xizang plateau. The grassland is destroyed wherever the pika population is in great number.This paper deals with the relations between the vegetation and the density of the pika in grassland according to the observations carried out in the alpine meadow of Men-Yuan, Qinghai, during August, 1980.The relation can be shown in the following binary linear regression equation. y = 101.34 - 0.8894x₁ - 0.1811x₂. y is the density of plateau pika, while x₁ and x₂ represent the cover-degree and height of the vegetation respectively.The result indicates that both the cover-degree and height of the vegetation influence the density of the plateau pika directly: the higher the cover degree and height of the vegetation, the lower density of the pika. The plateau pikas are difficult to be found in man-made grassland where the planted grasses are high.For control measure of the pika, it is important to improve the grassland.