In this paper, we propose a novel palmprint retrieval scheme based on principal lines. In the proposed scheme, the principal lines are firstly extracted by the modified finite radon transform. And then, a lot of key points located in three principal lines i.e. heart line, life line and head line are detected. Finally, the palmprints are retrieved by several key points' position and direction. The results of experiments conducted on PolyU palmprint database show that the proposed scheme is feasible and has high accurate retrieval rate with fast speed.