Abstract: Physiological effects of PP333 on Calcelaria crenatiflora were studled. It was found thatPP333 strongly suppressed growth and increaesd the activities of peroxidase and IAA oxidaseand the higher the PP333 concentration,he stronger the effects,PP333 iIcrased the chlorophyllcontent and decreased the soluble protein content in the leaves;t was suggested that PP333inhibited growth by increasing the activities of Peroxidase and IAA oxidase,esulting in low-ering of endogenous IAA level.