A manufacturing method of heat-sealable polyester film (Z, Z', Z"), comprising: physically regenerating a part of a recycled polyester material to obtain physically regenerated polyester chips, wherein the physically regenerated polyester chips have a first intrinsic viscosity; chemically regenerating another part of the recycled polyester material to obtain chemically regenerated polyester chips, wherein the chemically regenerated polyester chips have a second intrinsic viscosity less than the first intrinsic viscosity; providing a modified polyester masterbatch comprising a modifier, wherein the modifier is at least one selected from the material group consisting of 1,4-butanediol, isophthalic acid, neopentyl glycol, and polybutylene terephthalate; forming a heat-seal layer (2, 3) using the modified polyester masterbatch, the physically regenerated polyester chips, and the chemically regenerated polyester chips; and forming a base layer on the heat-seal layer (2, 3) to obtain the heat-sealable polyester film (Z, Z', Z"), wherein the physically regenerated polyester chips, the chemically regenerated polyester chips, and the modified polyester masterbatch are mixed according to a predetermined intrinsic viscosity, so that the heat-seal layer (2, 3) has the predetermined intrinsic viscosity, and the modifier is configured so that a heat-sealable temperature of the heat-sealable polyester film (Z, Z', Z") is between 100 °C and 230 °C, wherein the predetermined intrinsic viscosity of the heat-sealable polyester film (Z, Z', Z") is between 0.5 dL/g and 0.75 dL/g and a measurement method of the predetermined intrinsic viscosity is standard ISO 1628-1, and wherein, in the heat-seal layer (2, 3), based on a total weight of 100 wt% of the heat-seal layer (2, 3), the content of the physically regenerated polyester chips is between 50 wt% and 95 wt%, the content of the chemically regenerated polyester chips is between 1 wt% and 40 wt%, the content of the modified polyester masterbatch is between 0.1 wt% and 30 wt%, and the total content of the physically regenerated polyester chips and the chemically regenerated polyester chips is between 50 wt% and 100 wt%. physically regenerating a part of a recycled polyester material to obtain physically regenerated polyester chips, wherein the physically regenerated polyester chips have a first intrinsic viscosity; chemically regenerating another part of the recycled polyester material to obtain chemically regenerated polyester chips, wherein the chemically regenerated polyester chips have a second intrinsic viscosity less than the first intrinsic viscosity; providing a modified polyester masterbatch comprising a modifier, wherein the modifier is at least one selected from the material group consisting of 1,4-butanediol, isophthalic acid, neopentyl glycol, and polybutylene terephthalate; forming a heat-seal layer (2, 3) using the modified polyester masterbatch, the physically regenerated polyester chips, and the chemically regenerated polyester chips; and forming a base layer on the heat-seal layer (2, 3) to obtain the heat-sealable polyester film (Z, Z', Z"), wherein the physically regenerated polyester chips, the chemically regenerated polyester chips, and the modified polyester masterbatch are mixed according to a predetermined intrinsic viscosity, so that the heat-seal layer (2, 3) has the predetermined intrinsic viscosity, and the modifier is configured so that a heat-sealable temperature of the heat-sealable polyester film (Z, Z', Z") is between 100 °C and 230 °C, wherein the predetermined intrinsic viscosity of the heat-sealable polyester film (Z, Z', Z") is between 0.5 dL/g and 0.75 dL/g and a measurement method of the predetermined intrinsic viscosity is standard ISO 1628-1, and wherein, in the heat-seal layer (2, 3), based on a total weight of 100 wt% of the heat-seal layer (2, 3), the content of the physically regenerated polyester chips is between 50 wt% and 95 wt%, the content of the chemically regenerated polyester chips is between 1 wt% and 40 wt%, the content of the modified polyester masterbatch is between 0.1 wt% and 30 wt%, and the total content of the physically regenerated polyester chips and the chemically regenerated polyester chips is between 50 wt% and 100 wt%.