Im travelling with infant from sfo to Tapei thru China Airlines. wht is the baggage capacity allowd fr infant?

Check directly with the airline. On most airlines in all countries, if the baby is travelling in your lap, you get no baggage allowance but if you have purchased an infant's fare and a seat for the child you get the same baggage allowance for the child as you get for yourself.

An infant has no baggage allowance because he/she does not hold a physical seat. (Your lap doesn't count)