How to measure the quality of traded products scientifically and reasonably is a key issue in the study of the heterogeneity of enterprise product quality, but there is still a lack of a widely recognized method, and there is no relevant research to compare and test the results of different methods. Based on the three perspectives of import quality at the national level, export quality at the enterprise level, and import quality at the enterprise level, this article categorizes existing research methods, and uses China’s data for calculation and testing, striving to find the best fit for China's reality from different perspectives. The results show that: (1) The KHW method is used for the measurement of import quality at the national level, while the SHIBZ method is used for the measurement of export quality at the enterprise level, which is more in line with China's reality; (2) For the measurement of import quality at the enterprise level, by introducing transportation cost and exchange rate as the instrumental variables of product price, the existing method can be improved to overcome the problems of sample selection bias; (3) The measurement methods of the quality of trade products are divided at the national level and the enterprise level, as well as at the import level and the export level, and the calculation results can reasonably explain the quality change trend of China's import and export products in recent years. What’s more, the change trend of general trade import product quality at the national level and the enterprise level is consistent. The article not only provides a calculation basis for future research on the quality of China's import and export products, but also helps us to clarify the reality of China's import and export product quality and its changing trends.
