Hello Chen_Yan,
I would like to inform you that ReportManager Object was presented in HP ALM 11.00 OTA API.
In your case you have HP QC 10.00 and you have to look only in HP QC OTA API Reference Guide for QC 10.00.
You can find the document at the following URL:
http://support.openview.hp.com/selfsolve/document/KM749210
If you consider upgrading to higher version here are the guides for latest versions:
For HP ALM 11.00:
http://support.openview.hp.com/selfsolve/document/KM1097667
For HP ALM 11.50:
http://support.openview.hp.com/selfsolve/document/KM1413612
For HP ALM 11.52:
http://support.openview.hp.com/selfsolve/document/KM00425904
I hope this helps.