The general layout and the optimization of the basic design by the detailed design are introduced for the riser I-tube and foundation of the flexible dynamic riser jumper on an ultra-larger deepwater FPSO. The design of riser I-tube and foundation takes into account FPSO on-site operation, extreme environment, riser jumper offshore installation, riser accident, FPSO damage and ocean tow conditions. A quantitative analysis of the risk of the oil and gas leakage and the deflagration chain hazard has been carried out for the riser shutdown valves according to the enterprise standard requirements of the oil company. The design blast overpressure of the riser I-tube and foundation is determined to analyze the strength of riser I-tube and foundation against blast accidents. The passive fire protection design of the riser I-tube and foundation is also carried out. The fatigue life of the riser I-tube and foundation is finally predicted based on the analysis method of the cumulative fatigue damage.