Food plays a vital role in the survival of animals. Previous findings have shown that food restriction and food quality have a significant effect on body growth, endocrine, reproduction and other physiological characteristics. These results also indicated that changes in food consumption can affect breeding behavior and population fluctuation. Therefore, the present study aims to explore the effects of dietary protein content and food restriction on the physiology of adult female Microtu fortis. Forty animals were randomly divided into four groups and were allowed to acclimatize themselves to the following four regimens: (1) high-protein (20% protein content) and free-feeding diet, HF; (2) high-protein (20% protein content) and restricted to 70% free-feeding diet, HR; (3) low-protein (10% protein content) and free-feeding diet, LF; and (4) low-protein (10% protein content) and restricted to 70% free-feeding diet, LR. After a four-week treatment, body mass, estrous cycle, and fresh weight of the visceral organs (spleen, liver, kidney, and uterus) were determined. Female hormone level (estradiol, progesterone, and follicle stimulation hormone) were also measured using enzyme-linked immunosorbent assay. The results showed the following. First, the influence of food restriction was remarkable. When the food intake was restricted to 70% of the voluntary intake, the body mass significantly decreased, and the estrus period was shortened. Similarly, the fresh weight of the spleen, liver, kidney, and uterus was significantly lessened compared with that of the free-feeding groups. Second, the reduction in the level of protein content in the diet clearly lightened the fresh weight of spleen and liver. However, no significant difference was shown in terms of body mass and fresh weight of the kidney and uterus between the 10% and 20% protein content food group. Third, different protein contents and food-restricted degrees have no effect on the estrus cycle, serum estradiol, progesterone and follicle stimulation hormone level. In addition, an interaction between protein content and food restriction was not observed. In conclusion, the results indicated that when food resources are limited, female M. frotis reduced their body mass for basic survival, and accordingly, the fresh weight of their visceral organs was reduced. Compared with food protein content, the amount of food available played an important role in the physiology of adult female M. frotis. However, the role of food resources in the regulation of reproductive behavior and seasonal change in M. frotis needs further examination.