Abstract: The ecology of midday gerbil was investigated in E-JI-NA county of Inner Mongolia Autonomous Region from June to November 1980.Midday gerbil is a dominant species in the desert of the temperate zone and also a representative in the desert habitats. Their ecological characteristics can be shown as follows.1. The holes of gerbil are not very concentrate and they are mostly built around the unmoving sand dunes or under bushes. The tunnel structure is very simple and mostly with one opening. The length of tunnel is about 1-3 m and the depth only 40-70cm.The gerbils often seal the holes in summer.2. The gerbil is a nocturnal animal. The peak of activities appears at midnight in summer and autumn. The duration between entering and exiting from holes is about two hours, the moving distance from holes averages 263m. Midday gerbil often migrates with the change of foods and pherological periods.3. The breeding period of the perbil is rather long. Few females were pregnant even early November. The average embryo number was about 5.12. But the pregnancy rate after June was rather low and not more than 33.9%.4. Midday gerbil is omnivorous, taking a wide range of food. The 8.8% of their total food components is of animals'origin.Twenty-three among commonly existing plant species were consumed making up about 68%, among which the eating parts were either seed (43.6 %) or vegetative materials (40.9%) . Plant vegetative materials decreased gradually from June to Nov. The amount of daily intake is 33.5g, of which the vegetative materials made up over 50% during the plants growing season before July and while the seeds in stomach content were increasing gradually from 5% to 18.3g in August.