This paper designs a lightweight EtherCAT master and its test system based on Raspberry Pi. On the test system, the performance parameters of several parallel running masters are measured by multi-channel listeners, the delay jitters in polling/interrupt and single/multi-core modes are measured by means of software and hardware timestamp，and the delays and jitters of frame at each protocol layers are also measured. The EtherCAT master station based on Raspberry Pi adopts VxWorks operating system, the main optimization direction includes system kernel configuration, network adapter driver, message processing, application layer software, etc. By testing, the master has stable performance, the period jitter is about 6μs under 125μs period, which can meet the requirements of industrial field data acquisition, building automation, AGV control and so on.