Abstract: Fouling resistances of Songhua River cooling water in a plate heat exchanger were dynamically monitored and six kinds of water quality parameters of Songhua River at eight different times including dissolved oxygen,electrical conductivity,turbidity,Cl,alkalinity and Ca2 were tested,as well as the grey relational analysis was applied on the water quality parameters and corresponding fouling resistances.The water quality parameter analysis reveals that alkalinity has the greatest impact on the fouling resistance of the plate heat exchanger,and dissolved oxygen has the least influence.By analyzing the variation of water quality,it is found that the water quality parameters are closeted with the fouling.In the initial stage of fouling,the water quality parameters have significant effect on deposition,and it is decreasing latterly.Moreover,because of the interaction of different water quality parameter,the type of fouling is composite fouling including crystallization,particle,microbiology and corrosion fouling.But the crystallization and particle are dominant.Besides,it is the convective mass transfer that plays a great role in the fouling process due to high saturation in the bulk solution such as high alkalinity and calcium ion concentration as well as low flow velocity.