Abstract: Plantation is an important part of forest ecosystem in northwest Sichuan. In order to understand the forest quality status of the two typical plantations with spruce (Picea asperata) and radiata pine (Pinus radiata) as the dominant species, the forest quality assessment was carried out by using factor analysis and cluster analysis. The research results showed that: (1) Four principal components were extracted by factor analysis, and the cumulative variance contribution rate of the four principal components was 76.877%, which could comprehensively reflect the forest quality; (2) The weight values of the four criterion layers were as follows: timber growth factor> understory shrub factor > stand canopy coverage> understory herb factor, indicating that timber growth factor had the greatest influence on the forest quality evaluation index system. (3) According to the comprehensive score of forest quality evaluation, the proportion of sample plots in each grade was 10% in excellent condition, 40% in good condition, 10% in medium condition and 40% in poor condition, respectively. (4) There are obvious differences in the quality of plantions of different tree species in northwest Sichuan, among which the quality of spruce plantations was "good" and that of radiant pine plantations was "poor". This study is helpful to grasp the forest quality status of plantations in northwest Sichuan, thus laying the foundation for accurate improvement of forest quality in the future.