OBJECTIVE:To study the change regular of esterase isozyme and peroxidase isozyme of Polyporus umbellatus. METHOD:Using polypropylene amide circle electrophoresis.RESULTS：The pattern and activity of isozyme in same strain had some difference at different culture days,but some of isozyme pattern bands of the Rf value were visible in whole culture stage.Every strain had its peculiar pattern bands.CONCLUSION:The number of isozyme pattern bands and enzyme activity were proportional to the growing rate of myceliun,as well as its metabolic activity.