Spacecraft shield configuration is important in protecting the spacecraft from damages caused by small size space debris impact which could not be monitored. Improving the performance of the shield without increasing its weight and size has been a significant subject in the space debris shield research. Based on the fact that the ballistic limit of oblique impact is higher than that of normal impact, this paper introduces the "N" configuration to improve the shield performance with the oblique middle wall. According to the design, the middle layer of a triple-wall configuration was placed obliquely. The shield performances of this configuration and a parallel triple-wall configuration with the same areal density were compared and analyzed by 3D numerical simulation and hypervelocity impact tests. These results verified the validity of the introduction of oblique middle wall in improving the shield performance. The improvement is more notable with higher impact velocity.