Based on the digital waveform data recorded by Xinjiang Digital Seismic Network for the Xinyuan-Hejing ML6.8 earthquake sequences of June 30,2012，the paper analyzes stress drops of earthquake sequences and the correlation coefficients of focal mechanisms significant for strong aftershocks. Firstly，the source parameters of the Xinyuan-Hejing ML6.8 earthquake sequences are obtained by applying the spectrum analysis and the Brune's source model. Then，the correlation coefficients of spectral amplitude are calculated using the low-frequency spectral amplitude recorded by the same station for the different events. Finally，based on the results of the correlation coefficients of spectral amplitude，the events with similar focal mechanism are grouped using clustering method. The results show that：(1)The stress drop values show a steady trend in the aftershocks sequence calm period and the stress drop values show rise-fall in the strong aftershocks.(2)Moving average correlation coefficient of amplitude spectrum begins to spread after the main shock. It shows that the correlation decreases between the main shock and the aftershocks in mechanisms.(3)The results of focal mechanism groups show that the earthquake sequences are mainly strike slips. The stress distribution of the main pressure axis is nearly NS which is the same with the structural stress field.(4)The magnitude and mechanism show that there is an agreement before the strong aftershock，which shows that the regional stress field is enhanced.