Abstract: Polycyclic aromatic hydrocarbons (PAHs), especially high-molecular-weight PAHs, are the characteristic pollutants in coking contaminated sites, which are documented as highly toxic and recalcitrant to degrade. Due to the high controllability and high efficiency for insoluble organic pollutants, bioslurry reactor technology is a promising engineering process for soil remediation. To explore the variations of microbial communities after inoculation, and optimize the fluctuation range of solid content and the key parameters of microbial reaction, a self-developed 1 m³ slurry reactor tank combined with commercialized PAHs-degrading agent was adopted to conduct a pilot test at a representative contaminated field. The results showed that the microorganisms grew rapidly at the 3rd to 6th week under the stimulation of nutrients, reflected by the obvious proliferation of genus such as Hydrogenophaga, Sphingomonadaceae, and Pseudomonas, which were likely involved in the degradation of PAHs. Meanwhile, the concentrations of representative high molecular weight PAHs, namely benzoaanthracene, benzobfluoranthene and benzoapyrene, were reduced from several times the control target of Class 1 of building land in Soil Environmental Quality Risk Control Standard for Soil contamination of Development Land (Trial) (GB 36600-2018) to below the target value. In view of the lack of actual site pilot scale data in China, this study obtained reliable bioslurry reactor operation data and promoted the technology to engineering scale in China.