In this paper, a technology of ecological slope protection with polyvinyl chloride (PVC) pipe is introduced to improve the slopes’ erosion resistibility. Through establishing a large scale test model similar to the actual project, it is proved that PVC pipes could effectively reduce the soil erosion of slope by reducing rainfall erosion. The effect of PVC pipes is measured by the changes of soil erosion rate. As the experimental results show, the slope protected with PVC pipes are less damaged than the unprotected ones. For the protected slopes, the amount of soil erosion (q) increases over erosion time, and reaches a peak at 120 min, then it decreases and gradually becomes stable. Four hundred and eighty minutes later, the q of the bare slope, slope D75 (using PVC pipe with a diameter of 75 mm), slope D110 (using PVC pipe with a diameter of 110 mm), and slope D160 (using PVC pipe with a diameter of 160 mm) reduces by 25.2%, 85.9%, 78.9%, and 48.7% respectively, compared with the initial value. The q is significantly different with different diameter slope protection modes. There was a negative correlation between D (diameter) and q, and between T (time) and q. The cumulative erosion amounts (Q) of the four slopes, the same as q, increases over erosion time, and eventually become stable, which is a “S” shape shown in a statistic table. The Q is significantly different with different diameter slope protection modes. In addition, there was a negative correlation between D and Q. The time was positively correlated with Q. The average soil erosion reduction rates of the slopes (D160, D110, and D75) are 67.13%, 71.89%, and 79.96%, respectively, indicating PVC pipes' ability to cut down the infiltration of rainwater, the smaller the diameter, the more effective. The moisture content of the bare slope is the highest, followed by slope D160, then slope D110, and finally slope D75.