Objective： The variation characteristics of volatile flavor compounds in lemon pulp during vacuum freezing were investigated in this study, aiming to provide theoretical guidance for the regulation of the volatile flavor quality of the vacuum frozen lemon pulp. Methods： The analysis technologies of the electronic nose （E-nose） and gas-mass spectrometry （GC-MS） were employed to measure the volatile flavor compounds in fresh samples and frozen samples after 10, 20, and 30 minutes of vacuum-freezing, respectively. Results： The results showed that E-nose could be used to analyze different types of volatile flavor compounds in lemon pulp. The samples with different freezing time could be distinguished by principal component analysis and linear discriminant analysis. It was found by GC-MS analysis that the categories and the contents of volatile flavor compounds in lemon pulp decreased significantly during the vacuum freezing process （P<0.05）. The main volatile flavor compounds in lemon pulp are olefins, alcohols, and aldehydes, presenting a decreasing trend of fast first and slow later during vacuum freezing. Based on the heatmap and clustering analysis, the volatile flavor compounds appeared during the vacuum freezing process could be divided into 4 categories. After 10 minutes of vacuum freezing, the loss rate of D-limonene was the highest among the three different treatments. After 20 minutes of vacuum freezing, the loss of volatile flavor compounds was mainly due to the decrease in the content of olefins, alcohols and aldehydes, while the variation in the content of ketones was not obvious. After 30 minutes of vacuum freezing, new volatile flavor compounds such as 2,4-dimethylbenzaldehyde and 2,4-di-tert-butylphenol were generated. Conclusion： Most of the volatile flavor compounds in lemon pulp showed a significant decreasing trend during the vacuum freezing process, and some new compounds were generated.