With the comprehensive use of cross-hole seismic CT technique, ground penetration radar, high density resistivity method, shallow seismic reflection wave method, soil radon concentration and bore wave velocity test method,the authors detected geological hazards of karst ground collapse and ground subsidence in Jinshazhou area, Baiyun district of Guangzhou city. The distribution of karst caves, soil caves and tectonic fracture zones was detected. The authors utilized all kinds of methods and techniques and summarized the results of integrated geophysical techniques. With practical examples, it is proved that integrated geophysical techniques are efficient in the investigation of karst ground collapse and ground subsidence geological hazards, and can provide important basic data for geological disaster prevention. The first cross-hole seismic CT was applied to detecting the distribution of structures of underground karst in Guanghua basin, thus providing a basis for the safety of structures which are affected by karst geological hazards.