###### Abstract  
Under polycyclic aromatic hydrocarbon (PAH) pollution conditions (149.17-187.54 mg/kg), we had found the dominant flora of PAHs by observing the response of the soil microbial community after planting purple coneflower (_Echinacea purpurea_ (L) [PERSON]). In this study, pot experiments were conducted in a growth chamber to explore the changes in the rhizosphere microbial community structure during remediation of heavily PAH-contaminated soil using purple coneflower (_Echinacea purpurea_ (L) [PERSON]). The phospholipid fatty acid (PLGA) content in the soil was measured during four periods before and after planting, and the results showed that: (i) at 120 days, _E.  
and these values are on the rise [6]. Therefore, the removal of PAHs from the soil has become an important topic in the field of environmental research.  
Phytoremediation has developed in recent years as a safe and effective green remediation technology. Phytoremediation uses the synergistic action of plants and rhizosphere microorganisms to remediate contaminated soil. Compared with physical and chemical methods, its energy consumption and cost are much lower. Compared with ryegrass, white clover, and other plants, _E. purpurea_ has a short life-cycle and high tolerance to high concentrations of PAHs [7; 8]. Under high concentration stress, it exhibits the potential to remediate soil contaminated with high concentrations of PAHs. The removal rates of the four PAHs of pyrene (Pyr), chrysene (CHR), benzo(b)fluoranthene (BbF), and benzo(k)fluoranthene (BkF) were 66.2%, 70.3%, 40.6%, and 65.4%, and the total removal rates reached 56.93% [9]. The removal of organic pollutants by plants includes direct degradation and compound degradation. On the one hand, it relies on the direct degradation of enzymes produced by the root system. On the other hand, plants can synthesize various natural products and carry out the joint degradation of rhizosphere microorganisms when subjected to biological or abiotic stress. These two actions are based on the interaction of microorganisms and enzymes [10]. Therefore, the dynamic change in microorganisms can be regarded as an indicator of PAH degradation.  
Microorganisms in the soil are the most sensitive and rapid indicators for reflecting disturbances and biochemical changes in the soil ecosystem [11; 12], and the quantitative description of their community structure and diversity can be used as a potential tool for soil quality evaluation [13]. Analysis of PLFAs is a common method for the quantitative detection of soil microbial biomass [14]. The characteristic PLFAs of various bacterial groups are different, and these profiles are highly specific. Accordingly, PLFAs can be used as markers for different groups in the microbial community. Changes in the composition of phospholipids can reflect the changes in the microbial community structure in environmental samples [15]. Quantitative description of microorganisms provides relevant information for further research. In recent years, this approach has been widely used in the study of soil microbial community structure [16].  
Our previous studies have shown that purple coneflower (_Echinacea purpurea_ ([PERSON]). was able to remediate PAHs in contaminated soil [17]. The aims of this study were (i) to examine the changes in soil microbial community after planting _E. purpurea_, (ii) to look for the dominant bacterial flora to degrade polycyclic aromatic hydrocarbons under this condition, and (iii) through the discovery of the dominant bacterial group for PAH degradation, provide a direction for future research on functional genes.