The block caused by acerate algae was one of the reasons to filter station block in surface water treatment. A math model was used to analyze the correspondence about acerate algae removal, degree of filter tank block and backwash cycle. Through fitting the negative trend line ,the correspondence coefficient could reach 0.866 9. Some measures were studies and compared ,which were increasing PAC dosing concentration, dosing PAM, dosing active carbon, increasing chlorine dosage in water plant, having pre-chlorinating in reservoir raw water intake and so on.The technical experiments proved that chlorinating was the efficient process to remove acerate algae, the removal rate had direct relationship with T (reaction time) in chlorine dosing CT.