The quartz grains from basalt-derived chronosequence soils in Leizhou Peninsula and Hainan Island were examined under scanning electronic microscope for their external morphological characteristics. The results showed that in the same profile, the weathering degree of quartz grains was stronger in the surface horizon. During soil development, the weathering degree increased gradually from Primosols to Ferralsols phase (0.01~1.33Ma), and mechanically-formed features totally obliterated. In Ferrallitic soil phase (6.12Ma), decomposition phenomena occurred in quartz grains. This study confirmed the validity of the weathering score method of Darmody in the tropical area of China, and also showed that the surface weathering status of quartz grains from soil which developed from the same parent material and under the same environmental conditions can indicate the relative degree of soil development.