Abstract: Based on remote sensing interpretation, we found that the Jianchuan section of Longpan-Qiaohou fault zone has been active since late quaternary. The sinistral displace-ments of the rivers across the fault were divided into four grades of 40 m, 140 m, 550 m and 1040 m. T rench study showed that two magnitude>6.5 paleo-seismic events were ex-posed, one of which happened before 10010±40 a B. P.,the other happened between 6130±30 a B. P. and 6130± 30 a B. P.. Combined with previous research results, we conclur ded that three magnitude> 6.5 earthquakes had happened in the Jianchuan basin since Holocene, which happened respectively at 1751,6230±130 a B.P. and 10737± 468 a B. P.,the recurrence interval was about 5300 a. As the energy release of 1751 Jianchuan 6¾ earthquake is smaller than the first two and elapsed time is much longer, the seismic haz ard of Jianchuan section is worthy of attention.

Key words: Magnitude>6.5 paleo-earthquake, Recurrence interval, Jianchuan section, Longpan-Qiaohou fault zone