Kenaf plants are tall, flowers are bright, nectaries are developed, and there is a large amount of pollen, which is pollinated by insects or wind. The outcrossing rate is high (6% ~ 25%), the flowering period is long, the maturity time of individual capsules is quite different, the mature capsules are cracked, the seeds are easy to fall off, and the requirements for light and temperature are strict, so the mature seeds cannot be harvested in northern South China. Therefore, the main technical keys to ensure the quality and quantity of kenaf breeding are as follows: ① Choose a breeding site with good fertilizer and water, sow in time, and ensure that all seedlings are sown at one time. ② Strict isolation system. The breeding distance between varieties is 30 ~ 50m. Bagging and self-pollination are used to maintain the purity of varieties to prevent biological mixing of varieties. ③ According to the main morphological characteristics of varieties, such as leaf type, stem color, growth period, etc. Strictly remove impurities and remove bad ones. (4) Guangdong, Guangxi and Fujian provinces (autonomous regions) are suitable for seed production in autumn, while the southern part of Hainan Province is suitable for seed production in winter, and the northern hemp area is mainly based on "transferring seeds from south to north" combined with short-light seed production. ⑤ Harvest seeds in time. Germplasm resources should be harvested by single fruit, fully matured after harvesting, threshed in time and stored safely to prevent artificial mechanical mixing.