Aiming at two production risers with an outer diameter of 323.9 mm connected underwater, the safety risks of two different schemes, namely layout on the east side pontoon and layout on the west side pontoon of the "Deep Sea No.1" energy station, on the living building are quantitatively evaluated. The results show that when the risers are hanging on the west side pontoon of the energy station, the fire risk is significantly lower than when the risers are hanging on the east side pontoon of the energy station, while both of the two layout schemes meet the acceptable risk standard. “Deep Sea No.1” energy station adopts high-level safety strategy, the steel catenary risers with an outer diameter of 323.9 mm are hung on the west side pontoon of the energy station, H60 explosion-proof wall is used in the living quarter, and the leakage alarm system, abnormal production pressure alarm and shutdown system, mobile safety management system and safety fire-fighting system are comprehensively adopted to ensure the safety of the first deep-water self-operated gas field in China. The relevant practice can provide reference for the layout design and risk assessment of oil and gas riser system of other deepwater development projects in the South China Sea.