Fine mesh nets (FMNs) are commonly used as a mulch material to control soil erosion in construction spoil deposits. Here, three rainfall intensities (60–120 mm·h−1) and seven slope gradients (5°–35°) were considered in relation to an FMN’s function of reducing soil erosion on spoil deposits. Soil surfaces covered with an FMN (NS) were prepared in 2 m × 0.5 m soil boxes, with a smooth surface (SS) as the control. Runoff and sediment reduction benefits (RRB and SRB, respectively) were used to quantify the role of the FMN in soil erosion reduction. The FMN performed better in controlling the total sediment yield (mean SRB: 35.9%) compared with total runoff (mean RRB: 5.3%). There was a difference in runoff between SS and NS under a low rainfall intensity (60 mm·h−1; p < 0.05). SS and NS on different slopes generated similar runoff, with significantly different sediment yields (p < 0.05). The benefits of the FMN basically decreased with increases in the rainfall intensity and slope, although the RRB fluctuated on different slopes. The results demonstrate that the soil and water conservation benefits of the FMN on spoil deposits were influenced by the rainfall intensity and slope. The effectiveness of FMNs in soil erosion control needs further investigation in the context of local climates.