The regional horizontal deformation field and its variation around the epicenter area of the M_S7.0 strong earthquake in Jiuzhaigou, Sichuan was analyzed with the campaign GNSS observation data from 1999 to 2015, and the following views were obtained:① The hypocentral region of the M_S7.0 strong earthquake in Jiuzhaigou of Sichuan was deformed with dextral shear before the Wenchuan earthquake, and deformed with sinistral shear after the Wenchuan earthquake. ② The sinistral shear deformation in the hypocentral region has been weak since 2011, and the larger sinistral shear deformation is located in the southwest. ③The maximum shear strain, the maximum and minimum principal strains are weak in the hypocentral region. ④The occurrence of the Jiuzhaigou strong earthquake has a certain relationship with the extraordinary Wenchuan earthquake. The occurrence of the strong earthquake would be suppressed or postponed when the activity of the Longmenshan fault was locked, and the occurrence of the strong earthquake would be promoted or advanced when the activity of the Longmen fault was completely unlocked. ⑤ The southward coseismic displacement of 7.1mm occurred at the SCSP, the nearest station about 70km from the epicenter, but no coseismic displacement has been found at other continuous stations.