The invention provides a network flow prediction method and device based on a 
cognitive network. The method comprises the following steps of: carrying out least square method 
processing on an input 
signal X(t); outputting prediction sample data Y(t); carrying out 
wavelet transformation on the Y(t); decomposing the Y(t) into components with different frequency compositions; carrying out 
wavelet transformation on a coefficient sequence {D1(k), D2(k), ...... DL(k), AL(k)} at the k moment; training the network with the component {D1(k), D2(k), ...... DL(k)} as input of an Elman network and a 
wavelet coefficient {D1(k+T), D2(k+T), ...... DL(k+T)} at the k+T moment as output; training the network with the component of {AL(k)} as input of a 
linear network and {AL(k+T)} as output; training the network with each trained wavelet component {D1(k+T), D2(k+T), ...... DL(k+T), AL(k+T)} as input of a BP network and the original 
flow time {f(k+T)} at the k+T moment as the 
network output; obtaining the prediction output; introducing an LMS (Least 
Mean Square) 
algorithm to pre-process the input sample aiming at advantages and disadvantages of the traditional flow model and prediction method; inputting the input sample to a WNN (
Wavelet Neural Network) prediction model, therefore, the over-fitting problem in the traditional model is solved, and a more accurate model and prediction are provided for the network flow.