In this thesis, a new delay-based rate-control algorithm is proposed for a real-time video conferencing application. By implementing the new algorithm, the sender detects the current network condition based on the one-way delay variation trend of packets transmitted. Then the sender chooses the appropriate sending rate based on the current network condition. The new delay-based rate-control algorithm is implemented in a video conferencing application. The application uses a simple rate-control algorithm to control the sending rate. The sender detects the network condition based on the packet loss and the packet’s out-of-order feedback. In this thesis, the performances of both the new algorithm and an old one are tested on a test bed. Based on the test results, the new algorithm improves the performance of the application significantly compared with the old algorithm.