[Objective] To explore the effects of degradable mulch film mulching on runoff and loss of dissolved nitrogen and phosphorus. [Methods] Polyethylene film mulching (PF) with a thickness of 0.003 mm, degradable film mulching with a thickness of 0.006 mm (BF1), 0.008 mm (BF2), 0.010 mm (BF3) and 0.012 mm (BF4), and no mulch (CK) were set up. In in-situ runoff plots, using mulching on ridge tillage peanut planting as the study object, the runoff and concentration of ammonium nitrogen (NH₄⁺—N), nitrate nitrogen (NO₃^-—N), and available phosphorus (PO₄^3-—P) in runoff under natural rainfall conditions were measured, and the runoff and nutrient loss characteristics under different thickness of degradable mulch film were analyzed. [Results] (1) The degradation time of degradable film increased with the increase of film thickness. (2) The order of cumulative runoff was BF1＜BF2＜BF3＜PF＜CK＜BF4, and there was significant difference between BF1 and BF4 (p＜0.05). (3) Compared with CK, different film mulching can reduce the cumulative loss of nitrogen and phosphorus to varying degrees. BF1 had the most significant effect on reducing the loss of NH₄⁺-N and NO₃^-—N, while BF2 had the most significant effect on reducing the loss of PO₄^3-—P. (4) Among the five laminating treatments, the NO₃^-—N and PO₄^3-—P loss in BF4 treatment was the highest, while the NH₄⁺-N loss in BF3 treatment was the highest. [Conclusion] The research results can provide a theoretical basis for the prevention and control of water, soil, and nutrient loss in sloping farmland mulching with plastic film and solving the problems of agricultural non-point source pollution, and have important significance for green agricultural development and ecological sustainable development.