Some unforeseen downhole troubles often occur in the drilling course for various reasons， dealing with these troubles would waste a lot of time and cost much money. The paper introduces a new technology which can accurately forecast the downhole troubles ahead of time. Analysis was made on the variation of drilling parameters in drilling process by real time analysis with time series method, and according to the variation curves, the downhole troubles could be predicted. An application case and the remedial measures were elaborated. The study indicates that this new technology can reliably forecast downhole troubles 100~200 minutes ahead of time to greatly reduce the economic losses.