The Climate Experiment of Potato planting in the autumn was carried out in 2016—2017 by using the comprehensive scientific research base of Agricultural Research Institute of Liupanshui in Guizhou Province (average altitude 1 100 m).Based on the monitoring data of potato late blight and the daily average temperature, minimum temperature, relative humidity, precipitation and other data from August 15 to December 31 in 2016—2017, the meteorological factors and dynamic characteristics of the occurrence and prevalence of Potato Late Blight in autumn were analyzed and studied. The results show that: The main period of occurrence and epidemic of potato late blight is bud stage to flowering stage. In the bud stage to flowering stage, when the daily average temperature is less than or equal to 18 ℃ and the relative humidity is more than 75%, after 3 days, when the daily average temperature is more than 18 ℃ and the relative humidity is more than 75%, it is beneficial to the occurrence of late blight. It is suggested that the meteorological conditions should be taken as early warning indexes of potato late blight prevention in autumn, so as to actively organize prevention after the early warning indexes appear, so as to improve the control effect.