通过在线PCA来识别手势，并能对新增手势做一定的增量，很好的实现了增量学习。算法具有效率高，识别率好，速度快等特点，同样适合其他模式识别方面的应用。-The learning method for hand gesture recognition system based on vision is commonly off-line，which results in repeated off-line learning when new hand gestures come． Its real-time performance，expansibility and robustness are poor． In this paper，a method named online principle component analysis ( PCA) with adaptive subspace is proposed for hand gesture recognition． The subspace is updated online by calculating PCA of sample coefficients． The subspace updating strategy is adjusted according to the degree of difference between new sample and learned sample． The　algorithm is able to adapt to different situations and reduce the cost of calculation and storage． The incremental online learning and recognition of hand gestures are realized by the proposed algorithm． Experimental results show that the proposed method solves the unknown hand gesture problem，realizes online hand gesture accumulation and updating and improves the recognition performance of system．