In this study, the photostability of a CdTeSe/ZnS colloidal single photon emitter with a wavelength of 800nm at room temperature was investigated. The second-order correlation function was much smaller than 0.1, which proved that the CdTeSe/ZnS single quantum dot at 800nm is a highly pure single-photon emitter. The effects of the irradiation time on the optical properties from single quantum dots were analyzed. As the illumination time increased, the emission of biexciton and multiexciton in the colloidal quantum dots increased, and the occurrence of Auger recombination increased.