Embodiments of the present disclosure provide a method and apparatus for determining a cause of performance degradation of a storage system. The method comprises: monitoring performance of the storage system according to a predetermined policy; generating a performance degradation event from a result of the monitoring based on system performance baseline; in response to performance degradation event, obtaining information about the performance degradation; and offline analyzing the information to determine the cause of the performance degradation. Compared with the prior art, embodiments of the present disclosure can manage the system performance degradation effectively and continuously to minimize running costs and enable current performance profiling tools in the manner of insertion.