Abstract: To improve the performance of video transmission over Wireless Local Area Networks (WLAN), a dynamic mapping scheme based on Enhanced Distributed Channel Access (EDCA) is proposed. This scheme builds initially the importance-based sorting model for video data packets and computes statistically the average service rate for each access category of EDCA, and then sends dynamically the sorted video packets into different access category for transmission according to the available resources. Because the proposed scheme that modifies the still mode of packets mapping scheme in EDCA can make full use of the network resources, it improves the transmission performance for video transmission over WLAN. The experiment results show that the proposed scheme can reduces the transmission delay of packets and increases the quality of reconstruction images.