In this study,eight winter Brassica rapa cultivars were selected as materials,studied the relation between cold tolerance and botanic characteris-tics,growing period and dry matter accumulation.The results indicated:the eight winter rapeseed were divided into four groups:ultra winter-hardy cultivars,strong cold tolerance cultivars,cold tolerance cultivars and ordinary cold tolerance cultivars.The ultra winter-hardy cultivars(MXW-1,DQW-1)grew horizontally and their leaves were dark green or purple,their grow...