Abstract: Based on UAV imaging technology,images of the phenological period of Malus‘Prairifire’were collected,color parameter values（CIE L^*,a^*,b^*）were extracted,and color difference values（ΔE）for different sampling points of phenological periods were calculated.The dynamic monitoring of the flowering phenology of crabapple was realized by comparingΔE,in order to provide reference for grasping the dynamic phenological changes of crabapple in real time and making timely adjustment strategies,and also provide reference for flower phenological study.The results showed that,1)the color parameters of aerial images of M.‘Prairifire’were extracted by Photoshop software.The phenological periods were cluster analyzed based on the phenological color parameters,which could be divided into the germination stage,leaf spreading stage,budding stage,initial flowering stage,full flowering stage,final flowering stage,defoliation stage,fruiting stage,and dormant stage.2)The range of color differences in each phenology period（△E₁）and of adjacent phenological periods（△E₂）were obtained.A phenological discrimination method was established based on the maximum color difference△E_1max′in each phenological period and the minimum color difference△E_2min′between different phenological periods.3)The color parameters of M.‘Prairifire’phenological images on two dates(March 22^th and April 10^th)were randomly selected.The phenological periods of the two dates were determined by cluster analysis to be in the budding stage and full flowering stage respectively,which were consistent with reality.The color difference（ΔE₂′）of phenological images between the two dates was 21.8,which was higher than theminimum color difference from the budding stage to the early flowering stage(△E_2min=9.6).This indicated a larger phenological span between these phenological images,which were consistent with reality.In conclusion,this method could easily and efficiently judge the phenological stage of the flowering crabapple.