With 2 coniferous tree species and 15 broad leaved tree species as testing material, an air seasoning test of lumber was carried out at Haikou region. 25 mm was chosen as main thickness of the lumber, and a small amounts of lumber with 15 and 50 mm in thickness were tested as well. The final moisture content of 20% was adopted while analyzing the data, and the following results were obtained: 1 In a year, the low drying rates occurred in Jan., Feb., Nov. and Dec.. So these months are not suitable for air seasoning of lumber in this region. 2 Among the species studied, Cyclobalanopsis patelliformis and Engelhardtia roxburghiana had lower drying rates (<1.0), Podocarpus imbricatus, Adinandra hainanensis, Artocarpus styracifolia and Schefflera octophylla , higher drying rates (2.1～3.0), and the other ten species, medium (1.0～2.0). 3 If the drying rate of 25 mm lumber was held as the base number of 1.0,the corresponding values were 2.2 and 0.3 for the 15 and 50 mm lumber, respectively. 4 An analysis of multiple regression showed that, in the process of air seasoning,the moisture content of wood was the most important factor affecting the drying rate of lumber, followed by the relative humidity and temperature. The effects of wind speed and atmospheric pressure were not significant. 5 Significant differences were found in equilibrium moisture contents among the difference wood species tested, but not the thickness of the lumber. The average EMC ofthelumbertested was 17.2%.