Abstract: Based on smoothing the original data, the property of local extremum are employed in interpolating the envelope of data. From some numerical tests of seismic wave, the results reveal the improved envelope can effectively enhance the signal-to-noise of Source-Scanning Algorithm (SSA). However with respect to the non-source stochastic tremor, the SSA bright-function of this method brings on a little difference between the maximum and minimum. Additionally, there is obvious distinction in detectable-source and non-source tremor when the distribution of high bright-function value change as initial scanning time and scanning length. This distinction will be conducive to determine whether there is a detectable tremor source at one point in time.