Abstract: For hydrology report, based on method of trial and error to computate basin unit hydrograph, the initial assumption is difficult and the computation complexity of method of trial and error is large. But the manual intervention mechanism is established to make the initialization easier and the multithreaded method is used to make the computation faster. Based on manual intervention and multithreaded method of trial and error to computate basin unit hydrograph, numbers of multithread, assumption of initial unit hydrograph and computation of unit hydrograph are discussed.