Background: To investigate a method for standardizing intensity modulated radiation therapy (IMRT) optimization for nasopharyngeal carcinoma (NPC), in order to reduce the influence of subjective factors. Materials and Methods: This study is based on example IMRT plans for NPC, which were randomly divided into data acquisition and data verification groups. Organs at risk (OARs) were analyzed for various sub-organs. The data acquisition group was used for statistical evaluations of the mean value of the normalized mean doses of sub-organs. The data validation group was used to validate the findings. Results: Significant negative correlations were observed between the normalized mean doses of sub-organs for each OAR and the shortest distance between sub-organs and the target region surface. For each OAR, there was no statistically significant difference in the normalized mean doses of sub-organs between the data acquisition and verification groups (p > 0.05). Conclusion: The influence of subjective factors can be reduced by using the normalized mean doses of sub-organs for each OAR as the evaluation parameter for standardizing. This method is relatively simple; a majority of radiotherapy centers can apply the model for standardizing IMRT planning optimization based on the existing planning system.