The invention relates to a time synchronization precision test method for an intelligent device adopting IEEE1588 protocols. A time tester is used as a main clock, IEEE 1588 synchronous messages are sent to intelligent equipment to be tested for building the stable time synchronization; signal generation equipment simultaneously inputs switching value electric signals to the intelligent device to be tested and the time tester; the time tester and the intelligent device to be tested respectively capture timestamps of the input switching value electric signals, and the intelligent device to be tested generates generic object oriented substation event (GOOSE) messages to be sent to the time tester; and the time tester extracts the switching value input timestamps of the intelligent device to be tested in the received GOOSE messages, and the absolute value of the difference value of the timestamps and the timestamps of the time tester is the time synchronization error of the intelligent device to be tested. The time synchronization precision test method has the advantages that the time tester is utilized, the IEEE1588 protocols are adopted for carrying out the time synchronization, when the switching value input signals are changed, the timestamps during the switching value change are sent out through GOOSE messages, the message transmission real-time performance is ensured, and the test precision and the real-time performance are improved.