Abstract:In order to study the cloud characteristics of the southeast coast of China, a laser ceilometer CL5 by Vaisala was used to detect cloud characteristics in Xiamen from 1 January 2016 to 31 December 2020. By using the time proportion algorithm to calculate the cloud fraction, this paper analyzes the distributions of cloud layers, cloud-base height and cloud fraction via data analysis method. The results show that the cloud structure in the southeast coast of China is dominated by single-layer clouds (43.59%), supplemented by double-layer clouds (16.42%), and the probability of occurrence of clouds with more than three layers is rare (5.25%). During the observation period, there were mainly low- and mid-level clouds. Compared with that in other seasons, the concentration of cloud distribution density in summer is smaller, and the cloud-base height difference between the lowest layer cloud and the highest layer cloud is larger. High clouds are more likely to occur between 18:00 BT and 06:00 BT, especially in summer, showing the characteristics of obvious diurnal variation.