The fluctuation aggravation,critical slow-down and macroscopic ordering exhibited by the complex system in the fluctuation intensification stage are critical indexes before abrupt events in the modern statistical physics.The indexes are used in the short-impending prediction study of medium and strong earthquakes.The results indicate that the indexes also exist in the seismicity data in short-impending stage.To use the former two indexes can predict several possible occurrence dates of main shock and to use the latter index can determine the main shock epicenter.