We studied the food habits of Toad-headed Lizard (Phrynocephalus frontalis) collected in the Erdos region of Inner Mongolia using stomach dissection. The results show that Toad-headed Lizard prefers insects which account for 95.8% of all the food items in the period from August to September. No significant difference in food items was found between male and female although the index of food diversity (IFD) and the breadth of trophic niche (BTN) were greater in males than those in females. No any difference in food habits was found between adults and subadults or between subadults and juveniles, however, significant difference was detected between adults and juveniles. The percent similarity of food index was great between sexes and lower in different age group. The IFD and the BTN in different ages was the greatest in adults and the lowest in juveniles. The general beneficial coefficient, the beneficial coefficient in different gender and ages were V_Total=22.44%, V_Female=12.76%, V_Male=9.83%. The P.frontalis is a species beneficial to the desert steppe.