Earthquake prediction is a scientific challenge to the world's scientists. Being a complex natural phenomenon, earthquake has a quite clear physical nature, that is, a rapid shear fracture in the crust. Accordingly, earthquake preparation is the damage evolution process for the crust media, which eventually leads to catastrophic fracture. This is mainly a mechanical process. Considering this point and grasping the physical nature of seismogenical process, we have put forward a new approach to earthquake prediction in terms of Load-Unload Response Ratio (LURR) (Yin 1987, Yin 2006). In the present paper, we introduces the basic scientific problems, including how to load and unload the crust block, how to select proper geophysical parameters as response, and how to define LURR. Based on experiments, numerical simulations and damage mechanics analysis, the universal feature of LURR evolution before a strong earthquake has been revealed. More precisely, LURR fluctuates around 1 at the initial stage of preparation process, and then climbs to an anomalously high value (peak-point). Earthquake does not occur at this time. Instead, there is a delay time duration denoted as T2, which is related to the magnitude of the event. In order to predict earthquake in China，we propose to conduct countrywide spatial-temporal scanning of LURR, then to integrate with dimensional analysis so as to include more geophysical conditions into consideration. In this way, we have drawn up an approach to predict comprehensively the location, magnitude and occurrence time of forthcoming strong earthquakes. Finally, the practice of earthquake prediction with LURR has been retrospected.