This paper is a part summarization of cropland fertility investigation and quality assessment in Taicang, which is focused on changes of soil pH, organic matter, total-N, available-P, rapidly-available-K and CEC from 1980 to 2005. The results showed that cropland soil showed an acidification tendency. Organic matter and total-N contents were at middle or low levels, with slowed increasing tendencies. Available-P content increaseed obviously, but still at low level. Rapidly-available-K content was insufficient, with a decreasing tendency. CEC was at middle level, with a decreasing tendency. It suggested that effective measures should be adopted to prevent soil acidification and improve fertilization system, i. e., decreasing application of chemical N-fertilizers while increasing application of organic-, P- and K- fertilizers.