以夏玉米密度、氮肥、磷肥三因素三水平的设计（３３设计），进行了田间试验，研究处理数较多时完全方案与正交方案的优劣。结果表明，正交方案的试验效率高，几种不同的正交方案选优基本能达到与完全方案同样的效果。但进行因素水平间多重比较时，完全方案又因因素水平的隐匿重复多，试验误差较小而优于正交方案。 Field experiments were conducted with the design of three factors and three levels of summer maize density, nitrogenous fertilizer and phosphate fertilizer (33 designs), and the pros and cons of complete program and orthogonal program were studied when there were many treatments. The results show that the orthogonal scheme has high test efficiency and several orthogonal schemes can basically achieve the same effect as the complete scheme. However, when carrying out multiple comparisons between factors and levels, the complete scheme is superior to the orthogonal scheme because of the concealed multiple levels of factors and the small experimental error.