本文介绍了维生素 Ｄ２（以下简称 Ｖ Ｄ２ ）的光化反应与光照时间的关系，即由麦角固醇为原料，在与之转化所需的最佳匹配光谱照射下，找到 Ｖ Ｄ２ 的最佳光转化时间。结果表明，在２８３ｎｍ 波长的紫外荧光光源照射下，其转化效果最佳。在此条件下麦角固醇转化率随照射时间的增加而逐渐上升，但同时 Ｖ Ｄ２ 的异构体（副产物）也随之增多，因此综合以上两种因素，从而可确定１８～２１ 分钟是 Ｖ Ｄ２ 光化反应的最佳时间段。 This article describes the vitamin D2 (hereinafter referred to as V D2) photochemical reaction with the light time, that is, from ergosterol as the raw material, with the best match required for the conversion of light spectrum, to find the best V D2 light Conversion time. The results show that under the irradiation of 283nm UV fluorescent light source, the conversion is the best. Under these conditions, the conversion rate of ergosterol increased gradually with the increase of irradiation time, but at the same time, the isomer of v D2 increased accordingly. Therefore, by combining the above two factors, it can be confirmed that 18 to 21 minutes V D2 photochemical reaction of the best time period.