Hi scott.nemes
Thank you for giving me good advice.
I tries to use --use-master option but nothing has worked.
The problem still unsloved.
I applied the following patched and rechecked the behaviour.
[url]https://bugs.launchpad.net/percona-toolkit/+bug/962330/+attachment/3463314/+files/20121217_r2_pt-slave-delay.diff[/url]
The patch sloved the problem but other problem it generated the new problem.
Replication delay gradually become shorter and become 0 delay for the last time.