[Objectives] Understanding the competitive relationship of the sympatric Plateau Pika Ochotona curzoniae and Plateau Zokor Myospalax baileyi in their nutritional ecological niches is of significant importance for a proper comprehension of their roles and positions within the grassland ecosystem, as well as scientifically defining their potential hazards. [Methods] This study selected the dominant rodent species in the alpine meadows of the Qinghai-Tibet Plateau (Plateau Pika and Plateau Zokor), as research subjects, utilizing stable isotopes (¹³C and ¹⁵N) technology to investigate their nutritional ecological niches and interspecific relationships. [Results] Results showed that:(1) Enrichment of ¹⁵N and ¹³C stable isotopes in various tissues of the Plateau Pika and Plateau Zokor was shortest in their livers and longest in their claws and bones. The δ¹⁵N values in all tissues of the Plateau Pika were significantly lower than those of the Plateau Zokor, while δ¹³C values were significantly higher; (2) Within the tissues of the Plateau Pika and Plateau Zokor, the order of nutritional levels (NR), dietary diversity levels (CR), total area of the convex polygon formed by δ¹³C/δ¹⁵N (TA), and standardized ellipse area (SEA) were:liver < muscle < claws < fur < bones, and all four indicators in the Plateau Pika’s tissues were significantly lower than those in the Plateau Zokor (Table 2); (3) There was no nutritional niche overlap in liver, muscle and claw tissues of Plateau Pika and Plateau Zokor, but the degree of nutritional niche overlap in hair and bone tissues was 0.92‰2 and 1.17‰2, respectively (Fig. 2). And they all overlap among male populations. [Conclusion] To sum up, the nutritional niche of Plateau Pika and Plateau Zokor overlap only on a long timescale, while there is obvious differentiation on a short time scale.