Soil animals link the material circulation and energy flow between the above-ground and below-ground parts of the ecosystem, and play an important feedback control role for the structure, function and process of the ecosystem. As a typical large soil animal, surface beetles occupy an important position in the food web. Therefore, research on the δ¹³C and δ¹⁵N isotopic characteristics and nutritional relationships of surface beetles in different forest types is very necessary to understand the feeding characteristics of forest soil animals and protect the forest ecosystem. 31 species of 10 families and 31 species of surface beetles were collected from 6 different forest types in Xiaoxing'an Mountains Liangshui Nature Reserve. The stable isotope technique was used to determine the carbon and nitrogen stable isotope content in the beetles, and the δ¹³C, δ¹⁵N isotope and nutritional level differences of the surface beetles in different forest types were analyzed. The results showed that the δ¹³C and δ¹⁵N values of surface beetles in different forest types in June and July were significantly different (P<0.05), and the δ¹³C value in the original broad-leaved Korean pine forest and secondary birch forest was significantly higher than that of the larch plantation and the broad-leaved Korean pine selective felling forest. The δ¹⁵N value in the broad-leaved Korean pine selective felling forest was significantly higher than that of the other five forest types. The trophic levels of surface beetles in different forest types are significantly different (P<0.05), and the trophic levels of species within the forest types are not significantly different (P>0.05). It is between 2-4.5 trophic levels. Among different forest types, the difference in trophic level between June and July is Philonthus japonicas of the Paederidae in a Korean pine plantation, which has a difference of 1.28 trophic level. The carbon and nitrogen isotope ratios are significantly different (P<0.05), indicating that the beetle's food source composition is complex, the range of carbon to nitrogen ratios is large, the food source is diversified, and the degree of feeding specialization is low.