Abstract: Plateau pika （Ochotona curzoniae） is one kind of newly developing laboratory animals .Forty-two healthy pika （22 males and 20 females） from the fifth-generation of closed colony were measured for the weights of main internal organs. There was no significant difference statistically between the weight of organs in the male and female.Comparing with other laboratory animals, the relative weights of the heart and lung of plateau pika didn,t show obvious increase, this suggested that plateau pika adapted the plateau habitats by some mechanisms which have no relation to weights increase of its heart and lungs. Plateau pika was very well developed in intestinal system （almost 12 times as long as its bodylength）, especially in caecum （1.78 times as long as the body-length and has 57 circles of spiral ridges）, these were important characteristics for the pika to adapt the food resources under plateau environments.

Key words: Plateau pika, Internal organ weight, Intestine