Winter rapeseed （Brassica napus L.） cultivated in paddy fields frequently encounters waterlogging. To identify germplasm resources with strong waterlogging tolerance， 353 accessions were evaluated under to a 12 h waterlogging treatment at the germination stage. The electrical conductivity of the soaking solution was immediately measured after treatmen. Six growth traits， i.e.， root length， shoot length， root fresh weight， shoot fresh weight， root dry weight， and shoot dry weight， were determined after a 7 d recovery. Membership function analysis， principal component analysis， and clustering were used together with unit electrical conductivity to evaluate waterlogging-tolerance of rapeseed germplasm and to identify waterlogging-tolerant resources at the germination stage. The results indicated that all six traits significantly decreased after waterlogging treatment during the germination stage of rapeseed. The relative values （treatment/control） for root length， root fresh weight， and root dry weight were significantly lower than those for the shoot traits. Relative root length， relative root fresh weight and relative root dry weight supplemented with unit electrical conductivity can be used for waterlogging tolerance evaluation of rapeseed at the germination stage according to the analysis using a stepwise regression model and the correlation between various traits and the D value. These accessions were classified into four distinct groups using the comprehensive evaluation index （D-value）： extremely tolerant （D≥0.75，58 accessions）， tolerant （0.54≤D≤0.74， 111 accessions）， sensitive （0.32≤D≤0.52， 130 accessions）， and extremely sensitive （D≤0.31， 54 accessions）. The similar four-tier classification were classified according to unit electrical conductivity （Uel）： the extreme tolerant （Uel≤289 μS/（cm·g）， 32 accessions）， tolerant （290.42 μS/（cm·g） ≤Uel≤411.67 μS/（cm·g）， 146 accessions）， sensitive （411.90 μS/（cm·g） ≤Uel≤513.20 μS/（cm·g）， 110 accessions）， and extremely sensitive （Uel≥515.03 μS/（cm·g），65 accessions）. By integrating D-value （D≥0.95） and Uel （Uel≤204.48 μS/（cm·g））， six germplasm resources， including Ningza 2009 and Chuanyou 83， were identified as the most waterlogging-tolerant rapeseed. These materials， which exhibit exceptional tolerance to waterlogging during the germination stage， can serve as a foundational resource for investigating waterlogging tolerance mechanisms in later stages of rapeseed development and for enhancing waterlogging-tolerant varieties.