A polyethylene resin for a secondary battery separator, wherein the polyethylene resin is a single particle, and the polyethylene resin is composed of a first reactor polymer which is a homopolymer and a respective second reactor polymer which is a copolymer, which respective polymers are produced in a first reactor and a respective second reactor which are connected to each other in series to perform a continuous polymerization which results in the formation of single particles of the polyethylene resin, wherein the homopolymer is a homopolymer of polyethylene and the copolymer is a copolymer of polyethylene with propylene or butene, wherein the first an second reactor are hexane slurry or heptane slurry reactors, and wherein in the first reactor a low molecular weight homopolymerization is performed, further wherein the first reactor polymer is a low molecular weight polymer having a viscosity average molecular weight of 100,000 g/mol to 400,000 g/mol, which is calculated from the intrinsic viscosity according to ASTM D 4020, and wherein the intrinsic viscosity is measured according to ISO 1628-1 after dissolving for 70 minutes (1.2 hours) in a decalin solution at 135°C, and the second reactor polymer is a high molecular weight polymer having a viscosity average molecular weight of 1.5 million g/mol to 2.5 million g/mol, which is calculated from the intrinsic viscosity according to ASTM D 4020, and wherein the intrinsic viscosity is measured according to ISO 1628-1 after dissolving for 70 minutes (1.2 hours) in a decalin solution at 135°C, and the polyethylene resin has a melting point exhibiting a double peak in which a first peak is in the range of 125 °C to 132 °C and a second peak is in the range of 133 °C to 136 °C, wherein the melting temperature was measured using a DSC instrument, and by initially raising the temperature to 200 °C, maintaining an isothermal state for 10 minutes and lowering the temperature to 30 °C at a rate of 10°C per minute, and subsequently measuring the melting temperature while raising the temperature to 200 °C at a rate of 10 °C per minute, characterized in that the viscosity average molecular weight of the polyethylene resin is 500,000 g/mol to 1.2 million g/mol, which is calculated from the intrinsic viscosity according to ASTM D 4020, and wherein the intrinsic viscosity is measured according to ISO 1628-1 after dissolving for 70 minutes (1.2 hours) in a decalin solution at 135°C. wherein the first an second reactor are hexane slurry or heptane slurry reactors, and wherein in the first reactor a low molecular weight homopolymerization is performed, further wherein the first reactor polymer is a low molecular weight polymer having a viscosity average molecular weight of 100,000 g/mol to 400,000 g/mol, which is calculated from the intrinsic viscosity according to ASTM D 4020, and wherein the intrinsic viscosity is measured according to ISO 1628-1 after dissolving for 70 minutes (1.2 hours) in a decalin solution at 135°C, and the second reactor polymer is a high molecular weight polymer having a viscosity average molecular weight of 1.5 million g/mol to 2.5 million g/mol, which is calculated from the intrinsic viscosity according to ASTM D 4020, and wherein the intrinsic viscosity is measured according to ISO 1628-1 after dissolving for 70 minutes (1.2 hours) in a decalin solution at 135°C, and the polyethylene resin has a melting point exhibiting a double peak in which a first peak is in the range of 125 °C to 132 °C and a second peak is in the range of 133 °C to 136 °C, wherein the melting temperature was measured using a DSC instrument, and by initially raising the temperature to 200 °C, maintaining an isothermal state for 10 minutes and lowering the temperature to 30 °C at a rate of 10°C per minute, and subsequently measuring the melting temperature while raising the temperature to 200 °C at a rate of 10 °C per minute, characterized in that the viscosity average molecular weight of the polyethylene resin is 500,000 g/mol to 1.2 million g/mol, which is calculated from the intrinsic viscosity according to ASTM D 4020, and wherein the intrinsic viscosity is measured according to ISO 1628-1 after dissolving for 70 minutes (1.2 hours) in a decalin solution at 135°C.