Abstract: The mission of resistivity measurement device while drilling is usually used to evaluat the real time stratum data. How-ever, the collected information that reflects the resistivity signal contains a lot of noise components, so it is difficult to accurately reflect the formation resistivity information. Based on the algorithm of wavelet packet, the device of near-bit resistivity measurement can mea-sure resistivity of stratum at first time because of the method of measurement while drilling. It can decrease noise when measuring the side resistivity, bit resistivity and azimuthal resistivity, by the algorithm of wavelet packet and the best wavelet tree of reconstruct signal based on information entropy, .which increase the accuracy and reliability of resistivity measurement.