Abstract: Mixed species bird flocks are very common among tropical and subtropical forest birds, and their formation is of important ecological significance to birds. However, there is few research on the local temporal and spatial changes of mixed species bird flocks, especially on higher latitude and altitude gradients. From September 13 to October 5, 2019, the mixed species bird flocks in the Three Parallel Rivers region of Yunnan province was investigated in autumn by using the method of transect and sample point combination. The results showed that: (1) In terms of the time gradient, the occurrence frequency of mixed species bird flocks in a day was bimodal, that is, the frequency was higher at 8:00-11:00 and 18:00-19:00, reaching the peak at 8:00-9:00. (2) In terms of the latitude gradient: with the increase of latitude, the incidence of mixed species bird flocks decreased, and the richness and abundance of bird species in the mixed species bird flocks decreased; with the increase of latitude, the time distribution pattern that occurs in the mixed species bird flocks in a day shift from single-peak distribution to bimodal distribution, partial peak distribution and low-frequency distribution. (3) In terms of the elevation gradient: the frequency of the mixed species bird flocks in the middle elevation area (2400 m-2700 m) was higher, and the richness and abundance of the birds participating in the mixed group were single peak distribution at medium elevation; the latitude also affected the frequency of the mixed species bird flocks at elevation. At the same time, with the increase of latitude, the mixed species bird flocks was at the same altitude. The frequency of occurrence was reduced. (4) Mixed species bird flocks were almost all insectivore and omnivorous birds, and only the Carpodacus thura was herbivorous. The study confirmed that the mixed species bird flocks in the three parallel rivers region of Yunnan province had obvious characteristics of latitude and altitude gradient distribution, which laid the foundation for exploring the driving mechanism of the formation of mixed species bird flocks on a large environmental gradient.