Successional patterns in species diversity indices each vegetation stratum on the Loess Plateau, Ziwu Mountain, northwest China, were studied using the method of substituting spatial difference for time change. Relationships between species diversity and environmental factors were also studied using Canonical Correspondence Analysis. The results indicated that: (1) Herb layer species richness, evenness and species diversity decreased gradually during community succession (P＜0.05); Shrub layer species diversity and richness showed a J\|shaped trend, while evenness did not change significantly except in the Ostryopsis davidiana community (P＞0.05); Tree layer species richness, evenness and species diversity did not change significantly (P＞0.05); There was a significant hump\|shaped pattern in species richness along the temporal gradient, which agrees with the intermediate species\|richness hypothesis. (2) Canopy cover, the main factor correlated with species composition of both herb and shrub layers (P＜0.01), with soil nutrients and slope position having smaller effects. In contrast, slope position had a significant effect on tree layer species composition (P＜0.01), which might reflect recruitment differences. (3) Community succession in this area occurs due to species dispersal and environmental filtering. Changes in species diversity in the different layers were likely due to species′ differential responses to changes in light availability during community succession.