<p>The geological disease present in shallow underground space can pose serious safety hazards to various building facilities. There are many methods for underground space detection, among which the seismic scattered wave method is suitable for detecting isolated geological disease with smaller scale. Implementing the seismic scattered wave method on significant undulating surface but ignoring the difference in surface elevation, would affect imaging accuracy. The conventional elevation correction method is calibrating shot point and geophones to reference plane by correction velocity. Due to the unknown correction velocity, this method would cause errors in imaging results. We propose a seismic scattered wave direct imaging method for shallow underground space with undulating surface. The method is directly imaging based on common shot gathers, without the need of mapping to CSP gathers, making the calculation process simpler and faster. Based on the 3D scattered wave travel time formula, this method is no need to perform elevation correction on original shot gathers, thus avoiding errors and obtaining more accurate imaging results. We conducted model experiments to test the effectiveness of this method. The experiments show that the method has preferable imaging effects in shallow underground space with different surface conditions. We applied the method to a road construction site in mountainous area of Wuxi, Chongqing, China for karst cave detection. The actual detection results show that the method has high practicality and can be effectively used for shallow geological disease detection on significant undulating surface.</p>