Abstract: On the basis of the ecological survey conducted in July, 2007 in the northern waters of Liaodong Bay, the biodiversity and community structure of macrobenthos were studied using the multivariate analysis method to assess the ecological characteristics of macrobenthos and its relationships with environmental factors. The Shannon-Wiener index of macrobenthos in the survey area was 0-3.40, with average value 2.41; the corresponding Margalef's richness index was 0-2.40,with average value 1.58. These two biodiversity indices showed similar distribution patterns in the northern waters of Liaodong Bay, with low values mainly located in the northern adlittoral area, while the indices in other areas were relatively high and showed little spatial differences. A total of seven macrobenthicgroups were split out from these sampling stations for 20% similarity, exhibiting a nested distribution pattern in the survey area. There were four station groups whose biomass curves were above the abundance curves, indicating that the communities were not disturbed significantly. However, the biomass curves of the other station groups were very close to or intersected with the abundance curves,indicating that the communities were moderately disturbed. The combination of water depth, dissolved oxygen and total P content in the bottom waters produced the best match of all the environmental factors to macrobenthic assemblages; the relationship coefficients with abundance (R0.484) and biomass (R0.489) were all up to the significant level (P<0.01).