A fuel filter for a diesel engine, the fuel filter comprising: an upper cover forming inflow and outflow passages of diesel fuel; a housing integrally mounted in a vehicle body through a mounting bracket, coupled to the upper cover, and housing a filter assembly; a body forming a moisture drain passage that penetrates a central portion of the filter assembly, disposed between the upper cover and the filter assembly, and connected to an inner lower portion of the housing; a heater assembly installed at an inside of an upper end portion of the body; a moisture sensor installed in a moisture drain passage of the body and configured to detect a water level of moisture that is separated from diesel fuel; and a moisture exhaust portion that is provided in an upper end portion of the body in order to discharge moisture that is injected into the moisture drain passage and that penetrates the upper cover, wherein the body comprises: a head portion located between the upper cover and the filter assembly and fixed to an inner wall surface of the housing; and a stem portion integrally connected to the head portion, penetrating a central portion of the filter assembly, and forming the moisture drain passage, wherein a reinforcing plate that reinforces rigidity of the upper cover is bonded to a lower surface of the upper cover, and wherein a fuel exhaust nipple for discharging the diesel fuel from which moisture and a foreign substance are removed while passing through the filter assembly is installed in the upper cover, wherein the reinforcing plate is coupled to an upper surface of the head portion, wherein an exhaust flow channel for discharging the diesel fuel from which the moisture and the foreign substance are removed while passing through the filter assembly is formed in the stem portion, and wherein a connection flow channel that connects the exhaust flow channel and the fuel exhaust nipple is formed between the reinforcing plate and the lower surface of the upper cover in the reinforcing plate. an upper cover forming inflow and outflow passages of diesel fuel; a housing integrally mounted in a vehicle body through a mounting bracket, coupled to the upper cover, and housing a filter assembly; a body forming a moisture drain passage that penetrates a central portion of the filter assembly, disposed between the upper cover and the filter assembly, and connected to an inner lower portion of the housing; a heater assembly installed at an inside of an upper end portion of the body; a moisture sensor installed in a moisture drain passage of the body and configured to detect a water level of moisture that is separated from diesel fuel; and a moisture exhaust portion that is provided in an upper end portion of the body in order to discharge moisture that is injected into the moisture drain passage and that penetrates the upper cover, wherein the body comprises: a head portion located between the upper cover and the filter assembly and fixed to an inner wall surface of the housing; and a stem portion integrally connected to the head portion, penetrating a central portion of the filter assembly, and forming the moisture drain passage, wherein a reinforcing plate that reinforces rigidity of the upper cover is bonded to a lower surface of the upper cover, and wherein a fuel exhaust nipple for discharging the diesel fuel from which moisture and a foreign substance are removed while passing through the filter assembly is installed in the upper cover, wherein the reinforcing plate is coupled to an upper surface of the head portion, wherein an exhaust flow channel for discharging the diesel fuel from which the moisture and the foreign substance are removed while passing through the filter assembly is formed in the stem portion, and wherein a connection flow channel that connects the exhaust flow channel and the fuel exhaust nipple is formed between the reinforcing plate and the lower surface of the upper cover in the reinforcing plate. a head portion located between the upper cover and the filter assembly and fixed to an inner wall surface of the housing; and a stem portion integrally connected to the head portion, penetrating a central portion of the filter assembly, and forming the moisture drain passage, wherein a reinforcing plate that reinforces rigidity of the upper cover is bonded to a lower surface of the upper cover, and wherein a fuel exhaust nipple for discharging the diesel fuel from which moisture and a foreign substance are removed while passing through the filter assembly is installed in the upper cover, wherein the reinforcing plate is coupled to an upper surface of the head portion, wherein an exhaust flow channel for discharging the diesel fuel from which the moisture and the foreign substance are removed while passing through the filter assembly is formed in the stem portion, and wherein a connection flow channel that connects the exhaust flow channel and the fuel exhaust nipple is formed between the reinforcing plate and the lower surface of the upper cover in the reinforcing plate.