In this paper

the authors select 16 broadband stations recorded data from digital seismic network in Jiangsu Province

in which the epicentral distance ranges about 280

3

80 km.Then using the sliding window cross-correlation overlay technique to extract sPn phase

the focal depth of Gaoyou-Baoying M4.9 earthquake on July 20

2012 by sPn-Pn

is exactly determined to be 9.4 km

the total error range less than 1.2 km.In addition

in order to validate the calculation results

we used time-domain moment tensor inverse method

which has not arrival time of phases.By inversion of the different focal depth（5

2

5 km） models of the momen

t tensor solution

we find that when focal depth is 9

10 km

the inversion results of the correlation coefficient reaches the maximum

i.e.about 0.93

0.92.This indicates that 9

1

0 km is the best of focal depth range.Positioning result by the method of double-difference location with waveform cross-correlation is about 10.2 km.The difference is only 0.8 km.