Can I only deliver the changeset which associate to workitem which is in complete status

You should be able to accomplish this by setting the correct preconditions on the deliver operation.  Under "Operation Behavior" in your project area or team area, find Source Control > Deviler (server).  There are two preconditions that I think would be useful for you:

RTC was designed for the use case of developers who made the change also delivering the change set to the stream.  If you want to do things differently, such as having an SCM administrator who does all the deliveries to the stream, then things won't flow quite as smoothly.

When someone other than the developers deliver the changes, you are more likely to run into problems with gaps in the change set history.  For example, a developer creates a change set for work item #1, then creates a change set for work item #2 which depends on the first change set.  If work item #2 is completed before work item #1, it won't be possible to deliver the change set for work item #2 because of that dependency between the change sets.

Now that I understand that you want to have an SCM administrator (which was not clear in the original question), I suggest that you have two streams.  Developers would deliver to stream #1 as soon as they are done with their change sets.  The SCM administrator would move the appropriate change sets from stream #1 to stream #2 when the work items are complete.  If the two streams are owned by different team areas, you could set up different permissions for the two, such as configuring things so that only the SCM administrator (and not the developers) has permission to deliver to stream #2.

I don't know of an easy way for the SCM administrator to identify the change sets that should be delivered.  I am afraid that he will have to go through work items or change sets one at a time.  Setting up the preconditions as I described might be helpful, but it is not foolproof.  If the SCM administrator tries to deliver everything all at once and any of the change sets fails the precondition, then I think the entire delivery is aborted.  The SCM administrator would then have to go through the change sets one at a time deciding which ones should or should not be delivered.

https://jazz.net/jazz/web/projects/Rational%20Team%20Concert#action=com.ibm.team.workitem.viewWorkItem&id=140572 has some discussion on gated delivers based on builds , but the "gate" could conceivably be a configurable extension that enforces a rule by work item type that checks the status of work items associated to change sets.
It looks like something like http://pic.dhe.ibm.com/infocenter/clmhelp/v4r0/topic/com.ibm.team.build.doc/topics/t_ee_z_wi_promotion.html would be useful here.

Thanks for your reply David.
I think the No.2 pre-condition is in RTC v4.0 since I have not find it in the default pre-condition of RTC v301.
Actually my requirement is to select the complete work item's change set to deliver, so your method is to prompt error when deliver change set with work item which is not completed.
I think it is not bad to resolve my problem.

The hard work befor for the scm admin is he should choose what change set to deliver one by one. So I guess with your suggestion pre-condition, the admin can click deliver all and ignore the error for which can not match query?

What I prefer is there is a work item list, and I can use the scm tool to deliver the work item associated changeset. David what do you think about it?
Anyone have solution?
Thanks very much!