Taking 64 germplasm resources of pakchoi as test material，this paper adopted openfield
cultivation experiment and comprehensive evaluation on bolting tolerance of common pakchoi，
through analyzing bolting tolerance index，and carrying out principal component analysis on agronomic
characteristics，correlation analysis，membership function and clustering analysis．The results showed that
changing the 9 indexes into 3 principal components，including bolting time，plant growth state and growth
biomass by principal component analysis could increase their cumulative contribution rate to 79.147%．The
correlation analysis results showed that there was significant positive correlation between bolting stage，budding
stage and flowering stage．Among them，observation of budding stage was the most simple and reliable，
which could quickly evaluate the bolting tolerance of pakchoi．This paper divided these 64 germplasm resources
into 5 bolting-tolerant grades by membership function method，and screened out 4 extreme bolting-tolerant
germplasm resources and 6 bolting-tolerant resources．Clustering analysis put the above 2 kinds of germplasm
resources into theⅡ class group，indicating that both membership function method and clustering analysis
could effectively identify the bolting tolerance of pakchoi，but the membership function was more simple and
intuitive．