The monitoring system includes at least two probe ends located inside IP network, and control end in the IP network. The control end is in use for sending information of test configuration to probe ends, and receiving monitored data about network performance sent from probe ends. Based on information of test configuration to execute monitoring network performance between probe ends, the probe ends are in use for sending monitored data about network performance to the control end. The invention also discloses method for monitoring end-to-end performance of IP network. The invention raises test precision, and obtains accurate, valid monitored data. The measuring mode for testing quality of service in IP network disclosed by the invention is universal, end-to-end, round-the-clock, and diversified.