The study was conducted to find the dependency of polyploid inductivity rate of E.grandis clones’ axillary buds with colchicine on treatment conditions by applying Plackkett-Burman Design and Uniform Design. According to regression analysis, the functional relation equation between polyploid inductivity rate and independent variables including colchicines concentration and soaking time was found which value of Adj R-sq is 0.9366 and ideal. The maximum of inductivity rate can reach 51% when the soaking time is 26.2h and the colchicines concentration is 0.21%. The study result shows that the inductivity rises at fist and drops later with the continuous increase of colchicine concentration and soaking time. The inductivity drops because of the mass mortality of awaiting axillary buds.