When the compressed bitstream generated by a H.263 video coder is transmitted over the Internet

it is sensitive to packet loss. Due to the coding structure of the H.263 video compression algorithm

the packet loss can effect not only the current picture frame but also successive frame so that the quality of the video will be degraded seriously. The error concealment can be used to eliminate the effect. It commonly includes two methods : spatial concealment and temporal concealment. Spatial concealment uses the nearby correct image data of the corrupted part to recovery the image quality.The latter depends on the image data of the previous frame to estimate the lost data.However

spatial concealment will cause the blur of image quality and simple temporal concealment will make obvious artifacts. In this paper

we propose a temporal concealment algorithm based on block match principle. And in order to reduce the computational complexity

a new three step search algorithm is substituted for the exhaust search. Simulation results show that the proposed algorithm can produce acceptable quality of picture and can be implemented in the video conference application.