Embodiments of the present application provide a task allocation method and system. The method includes: analyzing at least one query pattern of a target task to acquire expected response time of the query pattern; estimating system cost information and estimated response time according to the query pattern and service description information; estimating node cost information of each processing node of a set of processing nodes in a computing system; selecting a processing node of the set of processing nodes according to the node cost information to allocate subtasks of the target task to the selected processing node; and determining an unallocated subtask in the target task to schedule the unallocated subtask according to the expected response time, the system cost information, and the estimated response time.