Based on the study of the ecoenvironmental geological evolution of the sedimentary column since more than 60 years ago in the Dalian Bay, it has been found that the variations of pollution degree can be divided into three phases: A (1933 - 1974) is a clean period, B (1974 - 1989) a relatively contaminating period and C (1989 -1997) a seriously contaminating period. Suppose the pollution degree of period A is zero, the pollution degree of period B is 8 times higher than that of period A, and that of period C is 25 times higher than that of period A. This indicates that the pollution degree has increased tremendously. Five elements, i. e. Cd, Pb, As, S and Zn, have incresed the fastest in content. The concentrations of Cd, Hg, Pb and As in the surface sediments of the Dalian Bay were 81. 42 times (Cd), 6. 0 times (Hg), 7. 54 times (Pb), and 3. 82 times (Zn) higher than the natural background values respectively in 1997. It shows that the pollution in the Dalian Bay is very serious. This study reveals that the biodiversity has decreased rapidly since 1950 in the Dalian Bay, indicating that the increase of pollution degree has greatly affected the life and health of humans.At present, Choushuitao in the Dalian Bay has a super polluted environment with very poor biodiversity, which is considered as a huge hiden chemical time bomb.