To satisfy the demands of hand recognition in computer interaction system, a fast robust hand segmentation and fingertip detection method is proposed. The procedure of segmentation consists of three steps: 1) Skin color segmentation, 2) Contour finding by freeman code, 3) Adaptive spline fitting of the contour. The hand could be segmented exactly step by step. Then, the accurate position of the fingertip was determined through the feature of the hand contour based on the segmentation. Experiments show that the proposed method works very well with high hand segmentation and fingertip detection accuracy in different condition, such as complex background, multiple hand direction and finger motion. It is appropriate for the hand recognition in human-computer interaction system.