(57) The present invention relates to an ethylene polymer and a process for preparing the same, wherein the ethylene polymer has an average particle size of 50-3000 µm, a bulk density of 0.28-0.55 g/cm³, a true density of 0.930-0.980 g/cm³, a melt index at a load of 2.16Kg at 190°C of 0.01-2500 g/lOmin, a crystallinity of 30-90%, a melting point of 105-147°C, a comonomer molar insertion rate of 0.01-5 mol%, a weight-average molecular weight of 2 ×10⁴ g/mol - 40 ×10⁴ g/mol, and a molecular weight distribution of 1.8-10. In the preparation process, raw materials containing ethylene, hydrogen gas and a comonomer are subjected to a tank-type slurry polymerization with an alkane solvent having a boiling point of 5-55°C or a mixed alkane solvent having a saturated vapor pressure of 20-150KPa at 20°C as the polymerization solvent in the presence of a polyethylene catalytic system, at the molar ratio of hydrogen gas to ethylene of 0.01-20:1, preferably 0.015-10:1, at the molar ratio of hydrogen gas to the comonomer of 0.1-30:1, preferably 0.15-25:1 to prepare the ethylene polymer.