Abstract: The carrier-s liability rules in the goods transportation by air is ve ry important in International Air Law. In order to protect the young aviation in dustry, the 1929 Warsaw Convention adopted fault presumed liability rules, which promoted the development of the air transport industry, but its shortcomings we re gradually exposed. The 1999 Montreal Convention introduced the strict liabili ty, which adapted to the new requirements of the development of the aviation ind ustry. This was mainly influenced by the change of social values, the developmen t of aviation technology, the inadequacy of the presumed liability rules, the co mplication and variety of the causes of accidents, and the protection of shipper s etc. This paper seeks to use the method of jurisprudence and comparative analy sis to research into this development process, and reveal the development trend of the diversification, specialization of the liability rules, the objective of the liability standard, the decreasing of the exemption, and the strengthening o f the shippers- interests.