Abstract: OBJECTIVE To improve the quality and utility of orthogonal experiments. METHODS The orthogonal experiments in published literatures were reviewed. RESULTS The common mistakes made in some literatures and outcomes were: orthogonal design or orthogonal table without blank column, resulting in inflating the random effect; baselessly ignoring the interactions, resulting in confounding bias; wrong results of analysis of variance (ANOVA) because of manual calculation; the selection of optimal process without considering cost-effectiveness, incurring cost increase of manufacturing. CONCLUSION Blank column of orthogonal table should be reserved for error estimated; the interactions could be ignored only when their existence are denied in relevant experiments and literatures; the data of orthogonal experiments should be analyzed using statistical software to make sure the accuracy of the results, and the cost-effectiveness should be considered in the selection of optimal process.