Plant functional traits, defined as morphophysiophenological traits which impact fitness indirectly via their effects on plant growth, reproduction and survival, which have been a hot topic of ecological and plant research in recent years. To elucidate the driving factors behind plant functional traits, especially in desertification grassland, we explored how variation in topography and soil characteristics affected plant functional traits in different desertification grassland including nondesertification grassland, lightdesertification grassland, middledesertification grassland and heavydesertification grassland in Northwest Sichuan. The results showed that: (1) plant community succession presented the pattern of “hygrophytemesophytexerophyte” with the aggravation of desertification degree. (2) The plant height and coverage decreased with the aggravation of desertification degree, and species richness and dominant species changed greatly. Moreover, leaf thickness (LT), specific leaf area (SLA), leaf density (LD), specific root length (SRL), root density (RD), leaf nitrogen (LN), leaf phosphorus (LP), root nitrogen (RN), root phosphorus (RP) decreased with the aggravation of desertification degree. (3) Nondesertification grassland had the highest plant functional traits with the higher efficiency of resource utilization. SLA had the higher variation (250.53), and LT had the lower variation (9.56), while RD, SLA, RN, RP, LD had the larger variation, then LT had a higher plant functional traits conservation. (4) RN had a strong correlation with plant functional traits, and SLA had a negative correlation with LD and positive correlation with RN. SRL had a significantly negative correlation with LN (P<0.01), and negative correlation with RN (P<0.05). (5) Stepwise regression analysis showed that plant functional traits had strong correlations with soil factors, which we can determine plant functional traits by soil factors. (6) Based on the grey correlation degree analysis, we can conclude that elevation was the most influential topographic factor on SLA, SRL, RD, LN, RP; while LT, LD, RN was affected by slope aspect; and LP was affected by slope position. Redundancy analysis showed that elevation and soil pH were the main driving factors to affect plant functional traits.