Abstract: Soil erosion and loss is most likely to occur around pipeline built in soil and rocky slopes of mountain- ous area due to rainfall, topography, soil conditions, destroyed vegetation and other factors. How to make the backfilled soil of pipeline trench stabilized in an effective manner is a major concern for the normal operation of pipeline. In this paper, analysis is given to the causes of soil erosion and loss around pipeline in mountainous slopes and introduction is presented to plastic drain board, a special geopolymer, in terms of its structural features, operating mechanism and application in the pipeline as mentioned above. Based on the technical and economic comparison between plastic drain board and cut-off wall, it is concluded that the employment of plastic drain board for hydrotechnological protection of pipeline in mountainous area involves less construction cost and provides more effective protection against erosion to the backfilled soil of pipeline trench.