The present invention discloses a method and an apparatus for allocating a stream processing unit, and pertains to the field of communications technologies. The method includes: obtaining a parallelism degree and a resource usage rate of a stream processing component on each computing node, and determining the number of stream processing units according to the parallelism degree; generating a stream processing unit to be allocated, and determining a resource usage rate of the stream processing component as a resource usage rate of a corresponding stream processing unit; and allocating, according to a processing capability of the computing node on which the stream processing component is located and a resource usage rate of an allocated stream processing unit, the stream processing unit to be allocated to a corresponding computing node. According to the present invention, the steam data processing efficiency of a distributed stream processing system is improved.