A video transmission system based on 3G WCDMA wireless network used in Micro Air Vehicle (MAV) was designed and implemented in order to improve the quality of video transmission and extend the transmission distance.The overall design and hardware architecture of the system were given using TI DaVinci processor TMS320DM355 as the core processor.The method for accessing WCDMA network using PPP dial-up was described.Video capture module based on V4L2(Video For Linux Two) was analyzed and designed，using embedded Linux operating system as the software development platform.The MPEG-4 compression and encoding process was implemented by calling Codec Engine API provided by TI.Real-time Transport Protocol (RTP) and Real-time Transport Control Protocol (RTCP) were used for the real-time video transmission requirement.The RTP packet strategy for MPEG-4 videos was described in detail and the real-time video transmission was implemented based on JRTPLIB library.Experiments showed that the system can satisfy the requirements for video transmission in clarity and real-time performance.