Abstract: The best sowing date of the potato Quanyun No.4 in southern Fujian was explored, in order to provide scientific basis for the high quality and high yield of Quanyun No.4. By taking the potato Quanyun No.4 as the experimental material, the experiments were conducted on the five sowing dates, including October 20 (stage Ⅰ), November 4 (CK), November 19 (stage Ⅱ), December 4 (stage Ⅲ), and December 19 (stage Ⅳ), thus to study the effects of different sowing dates on the growth period, yield, biological characteristics, the growth of stems and leaves and the development of tubers of the potatoes. In addition, the meteorological resources of each sowing date were compared and analyzed. The results showed that Quanyun No.4 was planted in winter in southern Fujian, and there were significant differences in plant height, stem diameter and fresh tuber weight per plant during each sowing date. During the early-sowing date, the stems and leaves were easy to grow excessively, while during the late-sowing date, the plant grew slowly and weakly in the early stage and the tubers expanded slowly in the late stage, with low yield, showing that they were not conducive to the high yield. The stem diameter of the potato planted on November 19 (stage Ⅱ) was the largest (12.4 mm), the daily fresh weight increased rapidly from 75 to 90 days after sowing, the tuber weight per plant was the highest (683.0 g·plant^-1), and the yield was the highest (35 655.0 kg·hm^-2). Under the conditions of this experiment, the potato Quanyun No.4 was planted in winter in southern Fujian, and November 19 was the best sowing date. Sowing in advance or delaying sowing excessively were not conducive to the yield increase of Quanyun No.4.