Linux virtual server (LVS) can establish a server cluster based on Linux with high availability, high capability, high reliabilities and scalability, while the weights of the weighted scheduling algorithm for the cluster load balancing system in LVS is static. Without the dynamic adjusting mechanism, the task can not been assigned dynamically according to the servers’ real capabilities. A dynamic load balancing algorithm (Multiplicative Regression in Critical Area，MRC) is introduced to adjust weights of the servers dynamically. The MRC algorithm calculates the load ratios and distributed weights according to the realtime feedback information from the real servers, and introduces the threshold regression factors to schedule tasks for web server cluster to achieve load balance. The method improves server's efficiency and the capability of the whole system. The method is applied to web server cluster systems based on Linux virtual server. The experimental results show that the algorithm can achieve realtime feedback of the load information, dynamic load scheduling, and achieve dynamic load balance in a whole, which improves the server utilization efficiency and the capability of the whole system.