Abstract: S-3307 of different dosages were sprayed at different timeson leaves of oil-tea trees and their effects to trees vegetative growth,blossoming and bearing fruit were studied. The result shows:when S-3307 of 500 mg/L(middle concentration) is sprayed on leaves on April 20,it restrains the growth of buds suitably,compared with check,shoot length,shoot diameter and single leaf area decreaseby 29.1%,9.1% and 5.6%,respectively;and the rate of flower bud differentiation,bearing fruit, weight/single fruit and fruit weight/single tree increase by 14.1%,33.6%,26.4% and 98.7%,respectively;it appears to promot the flower’s bud differentiation and fruit growth.When S-3307 of 250 mg/L(low concentration) is sprayed later (May 5),its effect is not obvious.The increase of output is low.When S-3307 of 1000 mg/L(high concentration) is sprayed early (April 5),the oil-tea trees vegetative growth and reproduction growth are restrained obviously,which resulted in the reduction of output.The experiment of separating one spraying into several sprayings (keep same concentration) shows that the effect of S-3307, to oil-tea trees is determined mainly by S-3307 concentration,little is concerned with spraying times.Besides,the experiment proves that S-3307 of suitable concentration can increase the content of chlorophyll,soluble sugar,soluble protein and praline in leaves,reduce the permeability of cell membrane,increase oil-tea trees heat resistance,drought resistance,cold resistance,reduce the number of fallen buds,fallen blossoms,fallen frutis,help to increase the output of oil-tea tree.