Abstract: We used six-year old Myrica rubra cv. Dongkui trees as experimental materials to study the effect of potassium chlorate on selected biological indices of M. rubra tree leaf during flower bud differentiation. The results indicate that MDA content and electrolyte leakage remarkably increase after spurting potassium chlorate, compared with the control. When potassium chlorate concentration is lower than 1 500 mg·L^-1, chlorophyll a and b, and total chlorophyll content obviously increase. SOD, POD and CAT activity is remarkably enhanced, resulting in a remarkable rise in net photosynthetic rate. Soluble protein content obviously increases while soluble sugar reduces during physiological differentiation. However, soluble protein content drops and soluble sugar remarkable rises during morphological differentiation. Soluble sugar to protein content ratio increases significantly, enhancing flower bud differentiation in M. rubra. When potassium chlorate concentration is higher than 1 500 mg·L^-1, chlorophyll a and b, and total chlorophyll as well as carrot contents drop, SOD, POD and CAT activity decreases, reducing leaf photosynthetic ability, soluble sugar content and soluble sugar to protein ratio. This suppresses flower bud differentiation in M. rubra. It can therefore be inferred from the study that 1 000 mg·L^-1 to 1 500 mg·L^-1 potassium chlorate remarkably enhances flower induction.