The stress drop and displacement during stick-slip under different normal stresses are measured in doublc.shear experiment. The coefficient of static and dynamic friction are obtained. The displacement-time curve during stick-slip is recorded by the instant wave recorder, then the seismic source time function is deduced, It's shape is similar to Brunet's time function,both decline as exponential function, it's Value is close to the site value measured in field. In order to make sure the experiment data reliable, the theory model of stick-slip is briefly analysed and calculated. The data obtained from laboratory, theory and field observation can be consistent with each other.