This paper mainly reviewed sustained +Gz acceleration-induced pathologic changes in various organ systems. Some of them are reversible and some may result in damage. Degree of the pathologic changes are related to G levels, G onset rates, duration of G exposure and individual difference factors. With raise of aircraft performance, acceleration problem is becoming more and more serious. Aviation medical workers should pay good attention to these changes and the use of high performance anti-G measures in order to ensure safety and performance of the pilots.