Abstract: The paper aims to study the correlation between of main inflorescence length and plant traits of hybrid Brassica napus, 649 combinations of Brassica napus were used for field experiment, laboratory test and correlation analysis. The results showed that: the average length of the main inflorescence of hybrid Brassica napus was 45.67 cm, the range was 28.00-66.65 cm, and there was few long main inflorescence. The variation coefficient of the length of the main inflorescence was small, the heritability was high, and it was not easy to be affected by the environment and suitable for early generation selection. The main inflorescence length showed significantly positive correlations with plant height (r=0.8262), main inflorescence pod (r=0.7804), pods per plant (r=0.7466), first branch number (r=0.4680), main inflorescence pod length (r=0.3164) and seeds pod (r= 0.2322), and had no significantly positive correlation with effective branch position and 1000-grain weight. The yield per plant showed significantly positive correlations with pods per plant, main inflorescence pod, main inflorescence length, plant height and first branch number. The main inflorescence pod length showed significantly positive correlations with seeds pod and 1000-grain weight. Using the correlation analysis, it could be seen that the selection of long main inflorescence material could effectively improve the plant height, main inflorescence pod, pods per plant, first branch number, main inflorescence pod length and seeds pod, so as to achieve the purpose of raising rape production. Considering current rapeseed production requirements of direct seeding or mechanical sowing with high density, materials of long main inflorescence length, more main inflorescence pod number, longer pod, and high yield per plant should be bred.