Abstract: A new geotextile technique is proposed to solve the slip problem of drainage channel in irrigation area of Ningxia Yellow River diversion. This new form of masonry protection is first attempted in the Ningxia region. This paper examines the effect of this kind of masonry. In this paper, the extended simplified Bishop formula under the condition of geotextile masonry protection is derived. The MATLAB calculation program is compiled according to this formula. According to the program, the four working conditions of farmland drainage channel are calculated. The four conditions are homogeneous soil slope, geotextile protection slope, homogeneous soil slope when considering quicksand layer and geotextile protecting slope when considering quicksand layer. The results of program calculation and the position of slip plane searched by program are compared with the results of geotechnical engineering software GeoStudio2007 and the actual prototype monitoring results. Finally, we come to the following conclusions. (1) The result of self-programmed program is in good agreement with that of GeoStudio2007 in the same mode, which shows that the result of self-programmed program is reliable. (2) The stability of homogeneous soil slope can be improved by about 33%in the form of geotechnical bag, but the effect is not obvious when there is quicksand layer in the bottom of the trench. It is suggested that the combination of geotextile and anti-slide pile should be adopted. (3) Field monitoring data show that the internal displacement of geotextile masonry slope increases with the increase of depth, which is basically consistent with the trend of slip plane position searched by the self-compiled program. (4) The internal displacement and annual displacement of geotextile masonry slope are smaller than those of traditional grass soil willow pile slope and the stability of the slope is high.