The study investigates the formation energies and charge transition levels of intrinsic point defects in lead halide perovskite CsPbBr3 using first-principles calculations. The results show that the dominant defect under Br-rich growth conditions has a much lower formation energy compared to moderate or Br-poor conditions. CsPbBr3 is found to be highly defect tolerant, with most intrinsic defects inducing shallow transition levels, while only a few defects with high formation energies create deep transition levels. This defect tolerance is attributed to the lack of bonding-antibonding interaction between the conduction bands and valence bands. The findings provide insights into the synthesis and optoelectronic properties of CsPbBr3, suggesting that moderate or Br-poor growth conditions can reduce defect concentration and maintain its good electronic quality.The study investigates the formation energies and charge transition levels of intrinsic point defects in lead halide perovskite CsPbBr3 using first-principles calculations. The results show that the dominant defect under Br-rich growth conditions has a much lower formation energy compared to moderate or Br-poor conditions. CsPbBr3 is found to be highly defect tolerant, with most intrinsic defects inducing shallow transition levels, while only a few defects with high formation energies create deep transition levels. This defect tolerance is attributed to the lack of bonding-antibonding interaction between the conduction bands and valence bands. The findings provide insights into the synthesis and optoelectronic properties of CsPbBr3, suggesting that moderate or Br-poor growth conditions can reduce defect concentration and maintain its good electronic quality.