Special Edge Load（SEL）of 8different kinds of refiner plates selected were calculated and fiber size（fiber length and aspect ratio）machined by these plates were measured.Regression model of the Special Edge Load and fiber length,aspect ratio were established.Analysis results showed that SEL had significant influence on fiber length and fiber aspect ratio,and influence on fiber length was more obvious than fiber aspect ratio,which could provide reference to fiber quality forecast,refiner plate type selection and design of grinding tooth shape of the plates.