In this paper, the observation data that the 3-component geomagnetic field reorded in deep borehole in Chongming Changjiang nong chang station and Pudong Zhangjiang station were analyzed by the method of wavelet transform .We discussed the observation way of geomagnetic field in deep borehole, data quality and noise characteristics.The result showes ：① there is obvious daily variation form and consistency for the data observed in deep borehole; ②the deep borehole observation can filter more magnetic interference that comes from space ;③the amplitude of noise  that recorded by deep borehole observation is smaller than the ground-based observation ,and the interference frequency range is more concentrated.