The wideband operation of multi-port reflectometer may lead to inaccurate reflection coefficient measurement caused by the overlapped phase characteristics of the used calibration standards. Therefore, a calibration procedure implementing Least Mean Square (LMS) is proposed to offer accurate operation of wideband multi-port reflectometer from 1 to 6 GHz. Its well wideband performance is verified by attenuators of 3, 6 and 10 dB that assessed as the device under tests (DUTs). The proposed LMS contains a learning rate,  and updated weight coefficient, W(k+1) to eliminate error and achieve the corrected reflection coefficient of DUT.