Abstract: Frequency, as a seismic parameter, is widely used in earthquake forecast. From the nonlinea r viewpoint, a method of the delamination statistics frequency is offered in earthquake short -temporary time forecast. Its significance is the reflection of a whole active scale of tectonic system, and whether the magnitude-frequency relation is in nonlinear state, the variation of the system fraction dimension and chaos state degree. In the course of the method operation, a concept of relative average distance of two borders upon arrangement frequency ratio has been introduced,increasing demonstration sensitivity of nonlinear process.Then sense of the time term prediction has been advanced. The da ta discussed in this pa per are taken from great North China region since 1970 to 1999. Result indicates that the credibility is bigger than 97. 5% . R -value is about 0. 32. In addition, the possibility to increase the synthetical forecast ability is provided by using multiple magnitude frequency change.

Key words: No n-linearity, Delamination, Frequency ratio, Short-temporary time forecast