The main mineral compositions and microstructures of the low-tenor bauxites from the Xiaoguan deposit, Henan province have been studied with SEM and EDX. These bauxites have been compared with the high-tenor bauxites. It is considered from this that for the low-tenor bauxites the mineral compositions are more complex; several kinds of mineral association are common; the main aluminium mineral is diaspore, but it is lower in purity; the microstructure is more compact than that of the high-tenor bauxites. There are less secondary leaching holes; the crystallinity is also lower. It may be one of the reasons why the performance of technical processing for the low-tenor bauxites is less.