Abstract：It is found that some abnormal signals like compressive pulses and tidal distortion of the 4component borehole strain observation at Guza station about a year before the Wenchuan Ms8.0 earthquake in 2008 and even continued to occur occasionally after the earthquake. The S transform was tried to apple to the field in order to carry out a further research into the abnormal signal characteristic from a different perspective. An analysis of 4component borehole strain observation from over 20 stations within 1500 kms from the Wenchuan epicenter showed that only in the observations at Guza station there were significant abnormal signals with the following characteristics: On the basis of the background signals, the signals with period of about 10 to 60 minutes increased before the Wenchuan earthquake and gradually decreased after the earthquake, meanwhile, the most powerful signals were background signals with the power enhanced before the earthquake and weakened after it.
