目的：合成阿法骨化醇，准确监测反应进程并判定反应终点。方法：以IR及UV法监测阿法骨化醇合成反应进程。结果：以IR及UV法能准确有效的监测阿法骨化醇合成反应进程，避免了反应不完全或过度反应导致副产物增加的弊端，提高了反应收率，且重现性好，收率稳定。结论：本方法操作简单、迅速、准确、有效，适合于工业化生产。 Objective: This paper is about synthetizing alfacalcidol, monitoring the reaction process and determining the end of the reaction. Method: Monitoring the process of the synthetic reaction of alfacalcidol by IR and UV. Results: This is an effective method to monitor the synthesis process and avoid the incomplete reaction or the overreaction, which can lead to the increase of the side product. Furthermore, the method increases the yield of the reaction and improves the good reproducibility. The yield is stable. Conclusion: The method is easy, rapid and accurate. It is suitable for the pharmaceutical manufacture.