A plot experiment was carried out to study the effects of nitrogen (N) application time on dry matter accumulation and translocation in potato plant as well as on tuber yield. Cultivar KX 13 was grown at one N application level (150 kg/hm2) and four application patterns. Compared with applying all N at planting, applying 2/3 of all N at planting while 1/3 at the end of tuber formation stage can boost the translocation of dry matter from vine to tuber and the tuber yield increased from 34.8 t/hm2 to 38.1 t/hm2, marketable tuber yield increased from 23.3 t/hm2 to 27.8 t/hm2 (P＜0.05), harvest index increased from 0.76 to 0.86(P＜0.05). The treatment with the 2/3 of all N applied at planting while the other 1/3 applied at early tuber formation stage or all N applied at the seedling stage and the end of tuber formation stage depressed tubers yield though marketable tuber ratio increased slightly. The results also demonstrated that the dressing N in season could not decrease the starch content and dry matter content of tuber.