The time-space evolution of seismic correlation length before Wenchuan M8.0 earthquake is analyzed.We use ellipse which long axis is coincident with the strike of main fault belt in source area as the spatial window in analyzing on growing correlation length,and design the corresponding optimization procedure.The result shows that the growing correlation length before Wenchuan earthquake could be observed,and the significance of result is tested by the random synthetic seismic catalog.The result rejects the...