In this paper, by using skin-color feature, especial location and pixel features of eyes in face area, an efficient face detection algorithm was designed. After face detection, discrete cosine Transform (DCT) was used to extract a set of observation, which is provided to train and recognize faces in the way of Hidden Markov Model (HMM). In order to solve the shortcoming that traditional motion detection algorithm can not be used to detect slow moving objects from an image sequence, an improved method was proposed by rebuilding the background.