The invention relates to a fuzzy control method over multiple peristaltic pumps of a blood purification instrument. The fuzzy control method comprises the steps that weight change values are collected; a control task distribution module correspondingly obtains flow accumulation errors of three pumps and flow accumulation errors of an ultrafiltration rate according to flow setting values and the weight change values of a waste liquid pump, a dialyzate pump and a fluid infusion pump; a fuzzy controller obtains PID controller indicator variables and fuzzy flow compensation values corresponding to the three pumps through the flow accumulation errors; the control task distribution module inputs the flow accumulation errors of the three pumps into PID controllers according to the PID controller indicator variables; the three PID controllers output PID flow compensation values; a flow-to-voltage module obtains target flow values according to the flow setting values, the fuzzy flow compensation values and the PID flow compensation values of the three pumps and converts the target flow values into voltage values; motor drive modules receive the voltage values and the drive the pumps respectively. Compared with the prior art, the fuzzy control method has the advantages of being simple in structure, high in precision, convenient to apply and the like.