In the past three decades, the application of the stable isotope technique to avian ecology has become increasingly widespread. The use of stable isotopes in the current studies relied on two principles. First, the isotopic composition of animal tissues reflects that of the diet in a predictable manner. Second, because tissues turn over at different rates, they integrate this information over different temporal scales and, if the animal is mobile, different spatial scales. This technique overcomes the limitations of traditional methods, especially in aspects of the different temporal-spatial diets, trophic structure of consumers, and trophic levels within the food web. In this paper, we summarize the preparation, working process, and data analysis of the application of stable isotope analyses in the avian diet and trophic structure. The paper also discusses the current progress of this technique in the origin of avian diets and trophic structure positioning. In particular, we review its main applications in terms of conservation and management: (1) to assess the impacts of habitat change on the population reproduction, (2) to detect the causes related to population dynamics, and (3) to estimate the nutrient allocation of reproduction in the breeding ground compared with that in the wintering ground. However, despite its potential, the technique is still regarded as a black box by many ornithologists. In most instances, these techniques did not fully take into account the limitations of stable isotope analysis as applied to avian ecology (for example, specific-species discrimination factor, different-tissue turn-over ratio, and isotope signatures). We also discuss the issues related to improvement and perspectives for the future application of this approach.