Abstract: In this paper, we have discussed the pseudo-synchronism and the addit-ional phase displacement created by "time-division" mode multi-channel data acquisition system when collecting the relative signals, the effect of additional phase displacement of data acquisition system on the results of MT data analyzed was tested by the MT records observed.we conclude that: The effect of the additional phase displacement, caused by pseudo-synchro-nism of data acquisition system, on impedance phase curve for magnetcotellu-ric deep sounding is notable.2) The effect of additional phase displacement on apparent resiseivity curve in the processing the magnetotelluric deep so-unding data is not obvious.