Using waveform data of Jiaokou, Douhe, Hunyuan and Haicheng earthquake sequences, the characteristics of corner frequency changing with the earthquake process is studied. In order to remove the magnitude affects which imposed on the corner frequency change trend, we obtain the ratio curves of corner frequency values in every event to corner frequency mean values with equal magnitudes in the same earthquake sequence.The curve shows the ratio changing process clearly:in the foreshock-aftershock pattern sequence, the corner frequency of foreshock is higher than that of aftershock if their magnitudes, are equal, but in swarm sequence this trend is not show.Using the mean value of corner frequency from small events in a larger area as the background value,we obtain the ratio curve which reflect the changing process of earthquake sequence also clearly. The method which gives the changing trend in a earthquake sequence could be a new way for earthquake prediction.