Different concentrations of PP333 solution have been used to soak buckwheat seeds. The effects of PP333 on buckwheat height, diameter, and the main stem branches have been studied through pot experiment. The results show that PP333 seed soaking has inhibited buckwheat height and diameter, but has promoted the branches of main stem; within the range of concentration, it dwarves height at the rate of 32.6 percent to 50.1 percent, and its enlargement range to the stem is from 11.7 percent to 21.8 percent