Abstract: To study the relationship between virus and bacteria in surface sediment, we conducted 3 cruises in May(spring), August(summer) and November(autumn) of 2012 in Dalian bay and Dayao bay.The abundance of viruses and bacteria were measured used the SYBR Green I method by epifluorescence microscopy.In Dalian bay, the results showed:the abundance of viruses in surface sediment varied in three seasons, and average abundance was summer spring autumn.The maximum value 1.59108VLP/g(wet weight) occurred in summer, and the minimum value 1.53106VLP/g occurred in spring.The viriobenthos horizontal distribution showed bay middle bay top bay mouth in spring, however bay middle bay mouth bay top in summer and autumn.The relationship between virus and bacteria was distinct(R2=0.80, n=20).In Dayao bay, the viriobenthos abundance of seasonal variations was summer autumn spring, and the maximum value was 7.08107VLP/g, the minimum value was 1.16106VLP/g.Dayao bay includes two groups, inner and outer.The abundance of viriobenthos was showed more in outer than in inner.The relevance between bacteria and viruses was not very well(R2=0.50, n=12).The ratio of viruses to bacteria in sediment was 4.12 and 4.09, respectively, which was similar in Dalian and Dayao Bay.The distribution difference might be in relation to environmental factors in two bays.