Transient electromagnetic methods have been widely used in geophysical exploration since 1980s,and have been developed for decades in China. Based on an analysis of transient electromagnetic systems developed by experts of various countries,the authors designed a new transient electromagnetic system called ATEM-II synchronized with GPS by using the timing signal of GPS and modern electronic devices. The system can be applied to such fields as mineral exploration, engineering investigation and underground water detection. Case studies and characteristics of the system are given in this paper.