Geology radar is a high-resolution engineering geophysical method which has abnormal reactions to karsts, water enriched zone, fault zones as well as the fractured zones and other geological phenomena in the front of the tunnel face. This paper discuss the principles of geological radar in advanced prediction, the layout method of surveying line and the data acquisition methods.The features of the structure and the permittivity difference between the adverse geological phenomena and wall rocks will also be discussed to design possible geological model to carry out forward modeling. The features of forward modeling such as the waveform, the frequency, as well as the amplitude is also the key point in this paper, and this paper summarizes the signal features of adverse geological phenomena in radar, theoretically and tries to do further researches on spectrum characteristic by analyzing the typical radar images, which will give clues to the development of the tunnel prediction.