As the first largest level-1 tributary of Nujiang River in Yunnan Province, Mengboluo River is featured with complex rainfall and runoff. The annual runoff series in Mengboluo River are obtained through restoration, interpolating and supplementing the observed data of runoff at seven hydrologic stations in the watershed. Statistical parameters are analyzed, and the linear relation with one variable, exponential relation with one variable, exponential relation with two variables are established between mean annual runoff of multiple years and drainage area of each hydrologic station, mean annual runoff of multiple years and mean annual precipitation of drainage area. Simulation and comparison are carried out from overall and regional perspectives. The simulation error of different relations from overall perspective ranges from ±19.6%-±11.5%, and the simulation error of exponential relation with two variables from regional perspective is within ±2.8%, indicating close relations between runoff and drainage area, and runoff and precipitation, which matches the hydrologic characteristics of Mengboluo River watershed. The method in the present paper could be promoted for plateau mountain area.