The present invention provides an elastic expansion method based on a container cluster and an application system thereof. The method comprises the steps of (1) creating a container cluster, and setting the threshold of elastic expansion, (2) judging whether a container in the container cluster is started or not, and executing a corresponding operation according to a judgment result, (3) setting a unified access point when all containers are started, (4) triggering elastic expansion when the indicator of the container in the container cluster reaches the set threshold, and adding or deleting the container, (5) in the elastic expansion process, adjusting the unified access point as a load balance strategy, which means that an access flow is always oriented to a viable container, (6) adding a new container into the range managed by the unified access point if the new container exists after the elastic expansion is completed. According to the method and the system, the number of the container cluster can be dynamically adjusted according to a monitoring data result, thus online application access in not influenced by application traffic, the maximization of resource utilization is realized, and the waste of resources in an idle time is avoided.