[Objective] A design scheme was proposed involving the addition of hydrophilic polyurethane (W-OH, a highly water-resistant material) under disturbed soil conditions to reconstruct a bottom water-resistant layer (approximately seamless impervious layer) in order to alleviate the adverse effects of water factors on the failure of disturbed soil to form frozen soil in a high cold mining area. Changes in slope infiltration, flow production, and sediment production of weathered coal gangue after the reconstruction of a water-blocking layer in an alpine mining area were studied to provide theoretical support for the recurrence of frozen soil on a disturbed slope and the prevention and control of soil erosion on a slope after the reconstruction of a water-blocking layer. [Methods] Simulated artificial rainfall was applied at rates of 60 mm/h and 90 mm/h to reconstructed water-blocking layers having W-OH concentrations of 0%, 1.5%, 2.5%, 3.5%, and 4.5%. Infiltration characteristics and soil and water loss changes of the weathered coal gangue slope under three different slope conditions (5°, 15°, 25°) were obtained. [Results] ① The stable infiltration rate of the coal gangue slope after application of a reconstructed water-blocking layer was significantly lower than that of natural slope, and was negatively correlated with W-OH concentration. ② The flow yield of the coal gangue slope showed a trend of rapid increase at first and then gradually becoming stable over time, and the average flow yield showed a positive correlation with the W-OH addition concentration. The average runoff yield of coal gangue slopes with 1.5%, 2.5%, 3.5%, and 4.5% W-OH increased by 26.75%, 38.02%, 46.90%, and 63.23%, respectively, compared with the natural state. ③ The average slope velocity was positively correlated with rainfall intensity, W-OH addition concentration, and slope, and the influence degree followed the order of rainfall intensity＞slope addition concentration＞W-OH addition concentration. ④ The variation curve of slope sediment yield over time was mostly a “unimodal” curve, which showed a rapid rise at first, then a slow decline and finally tends to be stable. The average sediment yield of coal gangue slopes with 1.5%, 2.5%, 3.5%, and 4.5% W-OH increased by 26.98%, 49.48%, 71.64%, and 94.01% compared with the natural state. [Conclusion] The reconstructed water-blocking layer significantly reduced the permeability of weathered coal gangue on the slope, thereby effectively helping the recovery and formation of frozen soil on disturbed slopes in high, cold, mining areas. However, the decrease in infiltration rate could make the slope more prone to runoff and increases sediment production on the surface, and therefore, certain soil and water conservation measures should be applied.