Abstract: Deepwater oil and gas extraction faces challenges due to narrow safe density windows. Double-layer pipe dual-gradient drilling presents a viable solution, differing significantly from conventional drilling in both system architecture and operational principles, thus necessitating experimental validation of its feasibility. Guided by fluid dynamics theory and the working principles of double-layer pipe dual-gradient drilling, a laboratory-scale experimental system was established. Experiments investigated the variation in lift pump pressure under different drilling fluid flow rates and return fluid flow rates. The study assessed the impact of these parameters on lift pump pressure and efficiency. Key findings demonstrate that the double-layer pipe dual-gradient drilling lift system achieves stable operation that the return fluid flow rate exceeds the drilling fluid flow rates at the drilling fluid flow rates of 20–35 L/s, and the maximum pump pressure can reach 3.5 MPa. Adjustment of drilling fluid and return fluid flow rates enables precise pressure regulation of wellbore, confirming the technical feasibility of this approach. This research elucidates how drilling fluid and return fluid flow rates influence bottom-hole pressure, offering an experimental foundation for pressure management in double-layer pipe dual-gradient drilling systems.