A method of manufacturing graphene material, comprising steps of: first oxidation by adding 10-40% (weight percent) sulfuric acid, sodium nitrate, and graphene to a reaction container in an ice bath, stirring for a period of a first stirring time, adding potassium manganate a first oxidant, and stirring for a period of a second stirring time, a weight ratio of graphene, sulfuric acid, and sodium nitrate being 1:1.5-0.5:1-6, a ratio of volume of sulfuric acid to weight of graphene being 15-60ml:lg; first heating by sealing the reaction container, heating up to a first heating temperature, and stirring for a period of a third stirring time, wherein the first heating temperature is 30-40°C, and the third stirring time is 10 minutes-1 hour; second heating by adding de-ionized water, sealing the reaction container, heating up to a second heating temperature, stirring for a period of a fourth stirring time, and forming a preliminary graphene oxide, wherein a ratio of volume of the ionized water added in the step of second heating to weight of the graphene added in the step of first oxidation is 30-98ml:lg, the second heating temperature is 80-99°C, and the fourth stirring time is 10 minutes-1 hour; second oxidation by adding de-ionized water to the preliminary graphene oxide, stirring for a period of a fifth stirring time, adding hydrogen peroxide solution as a second oxidant, and stirring for a period of a sixth stirring time, a ratio of volume of hydrogen peroxide solution to weight of graphene being 1-20ml:1g; separation by adding de-ionized water and hydrogen chloride solution, and removing a supernatant by a centrifugal machine to obtain a precipitant, the supernatant having pH within 7±1; drying by adding alcohol solution to the precipitant, and performing a heated-drying or freeze-drying process at a drying temperature from -20°C to 80°C for 4 hours-2 days to obtain a graphene oxide; first ultrasonic vibration by adding de-ionized water to the graphene oxide, and performing ultrasonic vibration through a ultrasonic vibration machine; reduction by adding a reductant, and gradually adding 25%(weight percent) ammonia solution to keep pH with 9-10, a weight ratio of the reductant to the graphene oxide being 0.5-5.0:0.5; second ultrasonic vibration by adding de-ionized water, and performing another ultrasonic vibration through the same ultrasonic vibration machine or another one ultrasonic vibration machine; heating by heating up to a third heating temperature, and stirring for a period of a seventh stirring time; and filtration by performing a suction-filtration process and a drying process to obtain a reduced graphene material, wherein a ratio of carbon to oxygen content in the graphene oxide is 1.14-2.81, and resistivity of the reduce graphene material is 1.45-150Ω/cm. first oxidation by adding 10-40% (weight percent) sulfuric acid, sodium nitrate, and graphene to a reaction container in an ice bath, stirring for a period of a first stirring time, adding potassium manganate a first oxidant, and stirring for a period of a second stirring time, a weight ratio of graphene, sulfuric acid, and sodium nitrate being 1:1.5-0.5:1-6, a ratio of volume of sulfuric acid to weight of graphene being 15-60ml:lg; first heating by sealing the reaction container, heating up to a first heating temperature, and stirring for a period of a third stirring time, wherein the first heating temperature is 30-40°C, and the third stirring time is 10 minutes-1 hour; second heating by adding de-ionized water, sealing the reaction container, heating up to a second heating temperature, stirring for a period of a fourth stirring time, and forming a preliminary graphene oxide, wherein a ratio of volume of the ionized water added in the step of second heating to weight of the graphene added in the step of first oxidation is 30-98ml:lg, the second heating temperature is 80-99°C, and the fourth stirring time is 10 minutes-1 hour; second oxidation by adding de-ionized water to the preliminary graphene oxide, stirring for a period of a fifth stirring time, adding hydrogen peroxide solution as a second oxidant, and stirring for a period of a sixth stirring time, a ratio of volume of hydrogen peroxide solution to weight of graphene being 1-20ml:1g; separation by adding de-ionized water and hydrogen chloride solution, and removing a supernatant by a centrifugal machine to obtain a precipitant, the supernatant having pH within 7±1; drying by adding alcohol solution to the precipitant, and performing a heated-drying or freeze-drying process at a drying temperature from -20°C to 80°C for 4 hours-2 days to obtain a graphene oxide; first ultrasonic vibration by adding de-ionized water to the graphene oxide, and performing ultrasonic vibration through a ultrasonic vibration machine; reduction by adding a reductant, and gradually adding 25%(weight percent) ammonia solution to keep pH with 9-10, a weight ratio of the reductant to the graphene oxide being 0.5-5.0:0.5; second ultrasonic vibration by adding de-ionized water, and performing another ultrasonic vibration through the same ultrasonic vibration machine or another one ultrasonic vibration machine; heating by heating up to a third heating temperature, and stirring for a period of a seventh stirring time; and filtration by performing a suction-filtration process and a drying process to obtain a reduced graphene material, wherein a ratio of carbon to oxygen content in the graphene oxide is 1.14-2.81, and resistivity of the reduce graphene material is 1.45-150Ω/cm.