Abstract: Under a complicated historical background,Chinese stock market has formed a very unique segmented market system with A,B and H share markets existing together.Through analysis on dual listed company’s share price and trading volume reaction to earnings announcement under different auditing standards,we found there are differences of information transfer,information evaluation and information reaction mode between A and B share markets.Then we discuss the causation of this difference in information efficiency and provide some corresponding policy suggestion.

Key words: market segmentation, information efficiency, earnings announcement