Abstract: Using diploid non-heading Chinese cabbage‘Yi-ling', the apical portion of their seedlings were treated with colchicine solution in different concentration.The variant plants were selected and identified in their ploidy, and were also studied in their characters of morphology, anatomy, cytology, their heat-tolerance, agronomic and nutritional traits.The results indicated that the treatment in colchicine 0.2 mol·L-1 for 4times resulted of tetraploid doubling in 7.64%.Comparing with the diploid plant, the tetraploid plants were significantly increased in the length and width of leaf and petioles, the number of flowering organs, stomata and pollen, the weight of leaf, petioles and plant, while setting percentage was receded remarkably.Based on the diploid plants, the contents of total soluble sugar, soluble protein and dry matter in autotetraploid plants were increased by 7.32%, 74.85%and3.91% for the leaves, and by 17.22%, 1.94% and 4.89% for the petioles, respectively.Similarly in the comparison, the content of organic acids in autotetraploid plant leaves and petioles was decreased significantly by22.56% and 25.00%, respectively.Under 42℃ heating stress, the content of MDA and free proline were significantly lower while soluble protein was higher in autotetraploid plants than in diploid plants.The results indicated that autotetraploid plants performed in high-quality and heat-tolerance.