For MT two-dimensional inversion of polylines profile, researchers usually use a separate profile inversion for each measured line profile, or conduct profile inversion with the type of "polylines bending straightening". The former of segmented inversion can't make the inversion results stitch up perfectly due to the boundary effect, and the latter inversion results can not reflect the true length of the measured profile, so that both situations affect interpretation work. The authors thus propose an improved method for two-dimensional polylines MT inversion. Firstly, a measured profile orientation is chosen as the fixed orientation of the MT two-dimensional inversion (usually, it is the longest one), the distance Li between each points is calculated on the adjacent measured profiles and the inflection point nearby, then the coordinate of measured points is rotated in a distance Li. In this way, the measuring points will be normalized to the original fixed orientation of the measured line, with progressively analogy. Finally, the two-dimensional inversion can be conducted for the new profile data. Based on applying this improved method, the comparative analysis of forward and inversion in different polarization modes and the verification results of measured data, the authors hold that this method can effectively resolve the problem of the influence of the boundary effect in the stitching position of MT two-dimensional inversion and can also reflect the maximum possible extent of the true length of the measured profile, thus improving the reliability of the inversion results and helping later comprehensive interpretation.