A cloud system for a big data process, and an operation method thereof. A cloud operation method of processing big data includes: receiving a cluster rule; monitoring a cluster resource and a cluster task; adding a cluster resource based on the cluster rule and a cluster resource monitoring value; and replicating a cluster based on a cluster rule and a cluster task monitoring value, wherein the cluster rule may include at least one of a resource assignment threshold value, a resource amount to be assigned, a task threshold value, and a number of replicated clusters.