Abstract: The clean, low-carbon and high-value utilization of semi-coke powder can not only improve the utilization efficiency of resources, but also reduce environmental pollution, which is conducive to realizing the national strategic goal of "carbon peak carbon neutralization". Herein, hard carbon as anode active materials for potassium ion batteries was prepared by carbonizing the semi-coke powder. The effects of carbonization temperatures on the carbon phase (highly disordered carbon, pseudo-graphite carbon and graphite-like carbon), carbon crystallite size, carbon layer spacing, defect concentration, surface properties of semi-coke based hard carbon were researched, and the electrochemical potassium storage properties of semi-coke based hard carbon with different microstructures were also evaluated. It can be found that with the increase of carbonization temperature (600～1600℃), the highly disordered carbon in hard carbon can evolve into the pseudo-graphitic carbon and graphitic-like carbon, the lateral size together with stacked size of carbon crystallite gradually increases. The content of sp³ hybridized carbon in hard carbon gradually decreases, which can evolve into sp² hybridized carbon, and the order degree of hard carbon gradually increases with elevating the temperature. In addition, the specific surface area and total pore volume of hard carbon decrease with increasing the carbonization temperature, and the mean carbon layer spacing increases first and then decreases. The hard carbon (ZN-1000) prepared at 1000 °C has the area ratio of 31.2% of highly disordered carbon, 34.5% of pseudo-graphite carbon and 34.3% of graphite-like carbon, and demonstrates the highest mesopore volume of 0.04 cm³/g, largest mean carbon layer distance of d₀₀₂=0.375 nm and some oxygen-containing functional groups such as C=O, C—O and —OH. As anode active materials for potassium ion batteries, ZN-1000 delivers a high reversible specific capacity of 207 mAh/g at a current density of 20 mA/g, and 32 mAh/g at a higher current density of 1000 mA/g. The excellent electrochemical potassium storage performances are closely related to the microstructure of semi-coke based hard carbon. K⁺ can be stored by adsorbing/desorbing on the highly disordered carbon, defects, oxygen-containing functional groups as well as open pores, and embedding/stripping in ordered carbon layers of semi-coke based hard carbon. The work can provide new ideas for the clean and high-value utilization of semi-coke powder and development of carbon anode materials for potassium ion batteries.