In order to better monitor metro Ethernet performance parameters

this paper proposes a method in compliance with ITU-T Y.1731standard

i.e.User-Definable Automatic Performance Monitoring（UDAPM）.It introduces the principle of performance parameter testing

expounds the principle of implementing the specific performance monitoring by the UDAPM module and analyzes its concrete design scheme.The experimental results indicate that this method is feasible as users can set the minimum time interval and relevant parameter threshold values and display the historical and real-time monitoring results. Its superiorities can be seen in the comparison with ITU-T Y.1731standard in several performance indexes.