The drilling stratum in the southern margin of the Junggar Basin is complex, and organic salt drilling fluid has excellent performance such as strong inhibition and high temperature resistance. At present, it is mainly used in the second spud of the well. The formation temperature of the third spud and deeper spuds is high, and the high-temperature resistant sulfonated drilling fluid and oil-based drilling fluid systems are facing severe environmental pressures, while the current organic salt drilling fluids face deterioration in rheology and fluid loss under high-temperature and high-density conditions. It is believed that the main factors affecting the performance of organic salt drilling fluids are fluid loss additives and weighting agents. A polymeric filtrate reducer HF-1 and nano-SiO2 plugging agent were added into an organic salt drilling fluid used in the second spud of the well, followed by optimization of barite particle size in order to develop a high-performance organic salt drilling fluid which favorably maintains its properties under high temperature and high pressure conditions. The laboratory tests revealed that the performance of the system is significantly improved compared to before, the developed drilling fluid having a density of 2.4 g/cm3 had a good rheology at 180℃. Moreover, the high temperature and pressure filtrate loss volume was 13.5 mL, but also the drilled cuttings recovery rate reached 97% with an expansivity rate of 4.7%. In addition, the tolerance to NaCl, CaCl2 and drilled cuttings of the developed fluid were up to 12%, 2%, and 10%, respectively, suggesting that the developed drilling fluid could provide a selectable high-temperature and high-density organic salt drilling fluid system for drilling complex deep well formations on the southern margin of the Junggar Basin.