The Qianguo MS5． 8 earthquake swarm of 2013 occurred in Qianguo，Jilin Province， China． There were 5 major earthquakes with MS≥5． 0 in the Qianguo earthquake swarm，the magnitude were MS5． 5，MS5． 0，MS5． 3，MS5． 8 and MS5． 0，respectively． In this study，we compared the characteristics of far-field seismic radiated energy of the major earthquakes based on the source spectrum and the ground motion spectrum of the earthquake swarm． We first research the ground motion spectrum of the 5 major earthquakes at the Changchun seismic station (CN2)， a National station，with the recorded ground motions． Then we calculate the far-field seismic radiated energy referred to the relationships of the source spectrum in order to describe the variable characteristics of the Qianguo earthquake swarm． Research results indicate that the second earthquake (No． 2) of MS5． 0 on October 31 was the key event of the earthquake swarm， which followed the first MS5． 5 earthquake ( No． 1 ) on the same day． In fact，the magnitude decreased of the No． 2 comparing with the No． 1 is not agreed with the larger far-field seismic radiated energy． It needs to point out that，the No． 2 is the turning point event of the Qianguo earthquake swarm，which is the significant transition before the largest MS5. 8 earthquake occurrence．