Abstract: The study of wetland food web is an important component in assessing the structure and function of wetland ecosystems. The trophic level of species reflects the nutritional relationships among species and the relative positions of species in the food web, and the changes of trophic levels can indirectly reflect the changes of wetland ecosystems. With the increasing application of stable isotope techniques in wetland food web research, it is necessary to select appropriate baseline species and discrimination factors to ensure the accuracy of trophic level calculations when using nitrogen stable isotopes. This study focused on the two key points of baseline species and discrimination factors in the process of trophic level calculation, and introduced four commonly used baseline species and two discrimination factors in wetland food web research. The influencing factors of baseline species and discrimination factors and their impacts on trophic level assessment were systematically analyzed. A summary was provided on how to select appropriate baseline species and discrimination factors in the future study of wetland food web, aiming to provide reference for the further research on nutritional ecology of wetland ecosystems.