Abstract: Based on the historical monitoring data of seawater, sediment and biological ecology in the fishery waters of northern Liaodong Bay from 2008 to 2017, a model of index weight evaluation was established by principal component analysis (PCA). The ecological environment quality of the sea area was evaluated comprehensively. The results show that the ecological environment quality of the fishery waters in the northern Liaodong Bay was at the level of light pollution, and the comprehensive pollution index was high on both sides of the east and west, low in the middle, high in the south offshore and low in the northern estuary. In the past 10 years, the comprehensive quality of the eco-environment in the study area was under light pollution except for the year of 2016. In 2011, the comprehensive pollution index was the highest, and the overall comprehensive pollution index remained stable, and show a trend of slight improvement year by year. Cluster analysis showed that the study area can be divided into four categories, with different characteristics. In the first category, the pollution contribution rate of bio-ecological indicators was the highest. The second category was concentrated in Shuangtaizi estuary, and the seawater pollution was obvious. The third category was characterized by heavy metal pollution in sediments. The fourth category was more widely distributed, and the comprehensive pollution index was among those of the other three categories. The pollution in the north of Liaodong Bay was mainly affected by bio-ecological indicators, whose contribution rate was 60.9%, and the contribution rates of seawater and sediment indicators were similar. Nutrients in seawater, heavy metal (Cd, Cu, Zn) in sediment, chlorophyll a and zooplankton were the main pollution indexes in Liaodong Bay, and their pollution contribution rates were high.