Thanks Dan.
Well, this does solve my label size problem. However, I don't know whether this way can keep the options I set in proc sgplot. For example, In proc sgplot, I can use tickvalueformat option to format the tick value, and I can use proc format to format the yaxis text tick values, and I can set the bigger font size of the data label beside each bar.
What are the equivalent ways to implement these parts in your way?
By the way, SAS provides a lot and very good documentations, but if they can come with examples especial when there are many options, then they become more helpful. Just take reference the documentations for other languages from Microsoft.
Thanks