Advancements of nonlinear science theory and method in seismic forecasting application are indicated and commented. In the respect of nonlinear mathematical models, the threshold regression model, the exponential model, and long-distance-relation ARIMA model .etc., successfully have been applied into the earthquake prediction in the medium term. In the fractals study, some new finding or discovery has been obtained for the previous experienced law or relation of the seismicity. In the dynamic mechanism studying, the multi-spring-block model as a better instance is analogous to the generating mechanism of earthquake by fault motion. For the multi-spring-block model, the dynamic equations with stick-slip friction law have been established and through the equations the typicaly. Nonlinear behaviors, such as limit cycle,bifurcation and chaos etc.,have been derived.The model is useful to development of probability prediction of an earthquake based on physics principle. The self-organization based on seismicity explained well some seismic activity law by means of cellular automata. And the Renormalization Group method for the criticality phenomenon of earthquakes has been applied into the medium-term earthquake prediction with an obviously physical significance.