Abstract: Spacecrafts operating in Ultra-Low Earth Orbit (ULEO) offer significant potential in remote sensing, emergency response, and global connectivity due to their high-resolution Earth observation capabilities and low-latency communication advantages. This study focuses on the aerodynamic drag of spacecrafts in ULEO, a key factor constraining their orbital lifetime, and conducts configuration optimization and experimental verification of an Air-Breathing Electric Propulsion spacecraft (ABEP). Based on the constraints of propellant balance and energy balance under the requirement of thrust-drag balance, the research team obtained the baseline configuration of ULEO spacecraft (model 1). For this baseline configuration, without reducing the spacecraft’s volume, air intake area, or solar panels area, an optimized design scheme was achieved by adding a tail cone angle to reduce drag, resulting in an improved configuration (model 2). To validate the design, systematic aerodynamic drag measurements were conducted on scaled models of both configurations using a high-precision micro-force balance system in the long-duration hypersonic rarefied gas wind tunnel at the Institute of Mechanics, Chinese Academy of Sciences. Experimental results demonstrated that the drag of the optimized model was reduced by approximately 1.8 mN compared to the original model, with a drag reduction rate of 11.0%, thus verifying the effectiveness of the conical design. In addition, the Direct Simulation Monte Carlo (DSMC) method was employed to numerically simulate the drag characteristics under different wall accommodation coefficients, thereby further investigating the influence of wall accommodation coefficients on the drag reduction effect of the tail cone angle. Through the aerodynamic characteristic analysis at small angles of attack ( ± 10°), it is verified that the improved configuration maintains a significant drag reduction advantage (with a drag reduction rate of 11.8% at a 10° angle of attack) even under real on-orbit attitude disturbances, while also improving the longitudinal static stability, which demonstrates promising engineering application potential.