Abstract: In order to reveal the characteristics of snowmelt-runoff and its influencing factors, a watershed at the Laoye Mountains in northern region of Da Hinggan Mountains was selected as an experimental object. Based on the experimental data, the characteristics of snowmelt-runoff were analyzed and it was found that three major affecting factors, such as temperature, rainfall and frozen-soil, were essential to snowmelt-runoff. The following conclusions were reached: snowmelt-runoff began on April 17 and ended on May 7 in the forest watershed in 2015. The process of snowmelt-runoff lasted for 21 days,the whole process of snowmelt-runoff had three different stages which were flood-stage, peak-stage and back-stage respectively. A mount of snowmelt-runoff fluctuated from 0.08 m³/s to 1.09 m³/s. After the May 11, snowmelt-runoff tended to 0.46 m³/s. Snowmelt-runoff had obvious difference of temperature between day and night in the early stage and later stage. However, the difference in peak-stage was not significant. The peak-runoff can be sustained and stable around 24 h. Snowmelt-runoff were significantly influenced by many factors especially temperature. The correlation coefficient between snowmelt-runoff and temperature was above 0.85, and the runoff was more sensitive to temperature than to other factors. The sensitive coefficient was up to 0.54. The melting of soil surface would increase the snowmelt-runoff,however,the melting of the soil below the surface would reduce the snowmelt-runoff. Rainfall can increase runoff in the flood-period, slow down drop-rate of runoff in the back-period. And the more rainfall, the greater driving-force.