A system detection method and apparatus. The throughput and response time of the system are acquired, where the throughput reflects the number of requests from outside the system that has been processed by the system. The response time reflects time required by the system to process requests from outside the system. The system performance characteristic parameter based on the throughput and response time is obtained and is used to describe congestion condition of the system to determine whether there is a bottleneck in the system. Also provided are a method and device for flow control. The system detection method and apparatus allow detecting a bottleneck and flow control in a simple and effective way to ensure that requests are processed in time.