Accurate track prediction is basis for improving the early warning capability for air threat situation of anti-collision, for this reason, an improved sliding window polynomial fitting track prediction method is proposed to intrusion aircraft. It mainly made two improvements: the first is to construct a suitable polynomial fitting equation for each predicted value in the sliding window for the prediction of several future values after the current values; the second is to adaptively adjust and fit the polynomial order and sliding window length according to the current track value and the target motion mode information reflected by previous finite continuous track value. Simulation result shows that, compared with traditional sliding window polynomial fitting method, the proposed method has better track prediction accuracy. It can improve the track prediction accuracy of non-cooperative aircraft to some extent, which validates its feasibility and effectiveness in track prediction.