Niche can reflect the functional status of species in the community. We can quantitatively study the relationship among intra-species, interspecies and habitat by the niche. In this paper, the dominant species of Larix gmelinii in the Greater Khingan Range secondary forest area is used as the research object, and the niche characteristics, niche width, overlap and competition relationship between degrees are analyzed using Levins formula, Pianka index and Hegyi single tree competition index models. Results show that the niche width first increases and then decreases regularly with the development of individual Larix gmelinii. The larger niche width tends to have a higher degree of overlap between individuals, and there is a significantly linear positive correlation between the niche width and the degree of overlap. There is no obvious correlation between the degree of niche overlap and the competition between each other, and there is a mutually beneficial niche overlap phenomenon in the Larix gmelinii population. The competition between individual organisms is related to the research scale.