Abstract: A digital filtering method is used in the initialization of T42L9 global spectral model. The experiments have been done on two initial conditions. Through filtering processes on the time series taken from short-time integrations of the model, the high-frequency gravity wave oscillations have been effectively removed from the initial fields and at the same time, the disturbances which are synoptically significant are reserved. Moreover, the analysed initial fields are little changed by the initialization. The results offive-day forecasts show that, after this initialization, the forecasts are more stable and the forecast fields are smoother. Comparative experiments show that the effectiveness of adiabatic and diabatic initial izations are quite similar. This initialization method is not only efficient but also very simple and convenient to implement, so it is a very practical method.