The key of the data validity of the phasor measurement unit（PMU） is the synchronization. The difference in the applied standards can cause to relatively bad consistency and interoperation. According to the comparison of the old and new IEEE synchrophasor standards， IEEE Std 1344—1995（R2001） and IEEE Std C37.118—2005， such key problems are discussed as synchrophasor， time tag and reporting rate etc. Resolving schemes for the realization and application of these problems are also proposed. According to total vector error（TVE）， the evaluation and error calculation methods for the static measurement precision and dynamic response characteristics of PMU are given. The improvement of the data transmission format is finally analyzed.