This article focus on the questions about jitter test in 10Gbit/stransmission system. For a long time the existing jitter transfer definition for STM-64 wasnot clear and widely accepted by china manufacture and operator. We compare the new revi-sion of G.783 in jitter transfer specifications which may be confused for engineers with heold version. As a question provided by our manufacture. The relation between jitter valueand “AIS”?would be helpful for the deep understanding about jitter principle. We makean analyses about this question.