The Northern East China Sea is a unique marine ecosystem with multiple environmental gradients (e.g. salinity, pH, and nutrients) along northwest to southeast, forming a horn-shaped pattern with Hangzhou Bay as the tip. This study applied 16S amplicon high-throughput sequencing with Illumina MiSeq technique and multiple statistical analyses to quantitatively reveal the relative contributions of local environmental conditions and regional spatial factors in shaping bacterial biogeographic pattern of coastal water using 95 surface water samples collected from 95 sites across 8 coastal zones, from Hangzhou Bay (northwest) to outside of Sanmen Bay (southeast), in the Northern East China Sea across a > 200 km scale.