2. Institute of Geophysical and Geochemical Exploration，Chinese Academy of Geological Sciences，Langfang 065000，Hebei，China

area of Beijing south-central axis，the disturbed magnetotelluric sounding data are analyzed and the interference characteristics of urban stray current on magnetotelluric sounding data are summarized． Based on the interference

characteristics，the remote reference method is selected for de-noising． Firstly，11 remote reference stations with different distances are used to process the remote reference of the measuring points，and the limitation of the single

station remote reference is analyzed． Then，the multi-station remote reference processing method with the optimal combination of different frequency bands is proposed． The full frequency band magnetotelluric sounding curves are

obtained by the optimal combination，which selected the processing results of remote reference stations at 80 km，220 km and 360 km away from the measuring points in the frequency bands ＞ 0. 044 00 Hz，0. 044 00 ～ 0. 005 50

Hz and 0. 005 50 ～ 0. 000 57 Hz，respectively． The research results show that the main interference mode of urban stray current to magnetotelluric sounding is near-field interference． The near field interference can be effectively suppressed after the multi-station remote reference processing of the data from the measuring point 27 km away，and the purpose of data quality improvement is realized，which is better than the single station remote reference processing．