Abstract: To enhance the robusrness of watermark,an improved watermarking algorithm based on wavelet transform was proposed. The level detail sub-image decomposed the original image using three levels discrete wavelet transform (DWT) were divided into non-overlap blocks. The blocks which were more adaptable to embed watermark,were selected by FCM on the block energy and HVS properties,and the cluster were used as the strength of watermarking on the adaptable blocks. The experimental results show that the embedded watermark is invisible,and also very robust.