Abstract: Based on the data of suspended matters, temperature, salinity and chlorophyll obtained in June and July of 2012, we discussed the distribution pattern of effective density of suspended matters and their influence factors on the shelf of the East China Sea in summer. The results show that the value of effective density of suspended matters is much higher in the offshore area than in the nearshore area. With depth increasing,the effective density of suspended matters in the nearshore area is also increased gradually and the value in the bottom water is higher than the value in its upper water; but the effective density of suspended matters in the offshore area remains relatively stable and the value in the bottom water is lower than that in the upper water. The distribution of effective density of suspended matters in the study area is chiefly affected by the Changjiang River diluted water, the coastal upwelling off Zhejiang and the submarine sedimentary environment, among which the main factor is the joint effect from the Changjiang River diluted water and the coastal upwelling off Zhejiang.