Based on data obtained from ERA-20C during 1900-2010, this study statistically conducted spatial - temporal characteristic and interrelation of boundary layer height (BLH) and aridity index (AI) in East Asia drylands, thus originally understanding dry-wet changes from perspective of atmospheric boundary layer. The results show high (low) BLH values generally coincide with regions that have small (large) AI values with a negative correlation for annual variability , and correlation coefficients were -0.469、-0.880、-0.947; and of which 61.3%、55.9%、55.9% of the years followed corresponding correlation, and 12.6%、8.1%、9.9% of the years reflected changes in BLH advanced AI changes for hyper-arid, arid, and semiarid regions, respectively; in addition, BLH and area of East Asia drylands exhibited a positive correlation coefficient of 0.651. These results indicate that there is a connection between BLH changes and dry-wet changes, confirming the phenomenon that changes in BLH drive dry-wet changes.