Abstract: Doctrine of equivalent is applied in patent infringement abroad. The new judicial interpretation amended the application of doctrine of equivalent in patent infringement and the cognizance of patent protection scope. The change of patent protection scope could directly influence the claims writing in patent applications. Based on the analysis of the change of doctrine of equivalent， a conclusion could be made that patent applicants would reduce technical features when writing the claims documents， and that the patent administration would meet more questions of lack of essential technical features in patent examination. Meanwhile the reduction of technical features could bring more questions of lack of creativeness.