现在从事投行，不知道短期目标和长期目标应该怎么确立，请指点！

That's too easy. Normally you need an MBA to move up to Associate level. Long term goal really doesn't matter, just pick up something really interest you.

I am right now a project manager in a local IB. I find the reason for MBA is weak!

You still can say every VP in your company has MBA title. So, it's nature to pursue an MBA for you.

To be honest, I would like to suggest you to be more concrete and personal on this goal if you want to differentiate from those hundreds of bankers every year. Try to be unique.

As for your first question, don't be nervous. Everything related with IB, IM or Corporate Finance is ok for your career goal. You can chose one as you like. ADCOM can understand it easily if only it is reasonable for you. Remember, they are specialists and they have interacted with too many bankers.

I think the major problem for you is to convince them that you are indeed working for an I-bank.

I heard in some south america countries, all the banks are investment banks. So ADCOM don't really take your I-bank as their I-Bank. You have to convince them.

so that means they care more about the short term goal, right?

what if I tell them, I will go back to china right after graduation? because in this way, I will not affect their employment rate. can they believe if I really want? does that make me more competent?

As long as you can convince adcom through in your application, it should be fine.