Natural video coding in MPEG 4 is concerned. The syntax structure of MPEG 4 video is illuminated followed by the general description of the video coding model. The key technology involved in the MPEG 4 video coding is analyzed in detail as follows: VOP generation;coding of binary and gray level α plane;motion estimation, motion compensation and motion prediction;texture coding;object based scalability include temporal scalability and spatial scalability;resynchronization, error concealment and error refreshment method provided by MPEG 4;sprite coding;zero tree wavelets based coding for still picture. The differences with other video coding standards such as MPEG 1, MPEG 2, H.263 are pointed out, which make the three distinct features of MPEG 4 stand out. The video application over the network based on MPEG 4 is shown, and the test results are given and analyzed.