Abstract:During 2018 and 2019 in Xinjiang Awat County of Aksu area of Xinjiang Academy of Agricultural Sciences test base, we investigated the effects of temperature on photosynthetic physiology and boll development of island cotton with the way of setup increase greenhouse field in full bloom stage for a 3 d (H3), 6 d (H6) and 9 d (H9) as treatments and with field state of nature as the control (CK). The results showed that: (1) the transpiration rate (Tr), intercellular CO2 concentration (Ci) increased and net photosynthetic rate (Pn) decreased in the relative leaves of boll with the increase of high temperature stress. (2) With the extension of high temperature and processing time, the cotton boll para leaf PSⅡ largest quantum efficiency (Fv/Fm), the actual light quantum yield PSⅡ (ΦPSⅡ), and photochemical quenching (qP), relative photosynthetic electron transport rate (ETR) showed a decreasing trend. While, the initial fluorescence (Fo) and nonphotochemical quenching (NPQ) showed an increasing trend, and the differences of H3, H6 and H9 were significant different compared with those of CK (P<0.05), among which the rapid rise or fall of each parameter mostly occurred in the 3 to 6 d continuous high temperature. (3) With the increase of high temperature stress time, the quality of cotton seed, fiber and boll shell dried matter decreased obviously. Boll number per plant, boll weight per plant, lint percentage and lint yield all showed a significant decreasing trend. In addition, the high temperature also affected boll development, resulting in the reduction of boll length and volume. The results showed that under the shortterm high temperature stress, the photosynthetic capacity of counterpoint leaves of island boll decreased significantly, which was mainly caused by nonstomatal factors. Continuous high temperature stress results in decreased PSⅡ openness, decreased electron transport capacity, and inhibited photosynthesis. Boll development and yield component factors are negatively affected, resulting in reduced yield.