A workload dispatch device and a workload dispatch method thereof are provided. The workload dispatch device comprises a monitor, a processor and a dispatcher. The monitor is configured to monitor operating conditions of a plurality of servers. The processor is electrically connected to the monitor and configured to execute the following operations: creating an average performance index table for a plurality of algorithms according to the operating conditions of the servers; normalizing the average performance index table; calculating a benchmark for each of the algorithms according to the normalized performance index table and a corresponding weighting table; and choosing a candidate algorithm from the algorithms according to the benchmarks. The dispatcher is electrically connected to the processor and configured to dispatch a workload to the plurality of servers according to the candidate algorithm.