The black-box model based on multivariate hybrid linear regression is applied for waterlevel simulation of the upper and middle reaches of the Heilongjiang mainstream

including the Mohe station

the Oupu station

the Sandaoka station

the Changfatun station

the Wuyun station

and the Qindeli station. The model structure is determined by AIC and DW method; parameters of the model are estimated by the least square method. The models are calibrated with day timescale hydrologic data of 2006-2010 in the flood season(May to September)

and verified with day time-scale hydrologic data in the flood season(May to September) in 2011. And the model's uncertainty and parameters sensivitity are analyzed. The results are as follows: ① The model is applied well in the Heilongjiang mainstream and accurate within acceptable range. Forecast schemes-pass rate reaches more than 85% and coefficients of determination are above 0.97 for six stations. The model can be used for water-level forecasting. ② The paper quantifies uncertainty of the Multivariate hybrid linear regression model results using the Monte Carlo methods. The larger the standard deviation

the more uncertain the flood hydrograph forecasting

and thus model is more uncertain. The parameters-sensitivity analysis based on standardized regression coefficients shows that the parameters with minimum values in time order of mainstream are the most sensitive

the parameters with minimum values in time order of tributary take the second place

and the parameters with higher values in time order are less sensitive.