The study of moso bamboo expansion mechanism can provide a basis for promoting scientific management of forest resources and improving the effectiveness of forest rights system reform. In this study， we selected the quantifiable phenological factors （stand spectral characteristics， stand density and stand leaf area index） in the process of the expansion of moso bamboo into cedar forests， and constructed a comprehensive phenological feature monitoring model to analyze the relationship between the comprehensive phenological feature index and the degree of expansion， so as to reveal the dynamic changes in the expansion of moso bamboo into cedar forests. The acquisition of each phenological factor was carried out by obtaining the stand spectral characteristics and stand leaf area index through vegetation indices of UAV multispectral images； the object-oriented multi-scale segmentation was used to obtain stand density. The results showed that the composite vegetation index， stand density and stand leaf area index of the spectral features of the stand all tended to increase with the degree of expansion， and the yellow factor of the spectral features of the stand tended to increase； the composite index of the apparent features was 0.348×composite vegetation index + 0.054×yellow factor + 0.041×stand density + 0.558×stand leaf area index. The composite index of apparent characteristics was positively correlated with the degree of expansion （R² = 0.574）， and it is reasonable to use the composite index of apparent characteristics to indicate the degree of expansion of moso bamboo， and the composite index of apparent characteristics increased with the degree of expansion.