A method of manufacturing a field emission electron source, the method comprising: forming one or more fixed emission sites on a needle tip, the emission sites including a reaction product formed by metal atoms on a surface of the needle tip and gas molecules under an electric field, the emission sites are rooted on the surface of the tip, rather than dissociative on the surface of the tip, since the emission sites are the reaction product formed by metal atoms fixed on the surface and the gas molecules; wherein the gas molecules include hydrogen-containing gas molecules, or hydrogen-containing gas molecules and any one or more of the following: nitrogen-containing gas molecules, carbon-containing gas molecules or oxygen-containing gas molecules, wherein a material of the metal atoms comprises one or more of: tungsten, tantalum, niobium, molybdenum, rhenium, hafnium, iridium, osmium, rhodium, ruthenium, platinum, palladium, gold, chromium, vanadium, zirconium, titanium, and metal-hexaboride, wherein a temperature of the needle tip is lower than or equal to 1, 000K, and a pressure is less than or equal to 10 -3 Pa; wherein the electric field is obtained by applying a bias voltage; wherein the applying a bias voltage includes any one or more of the following: applying a positive bias voltage, applying a negative bias voltage, or a combination of applying a positive bias voltage and applying a negative bias voltage, in a case where a negative bias voltage is applied for forming the emission site, the negative bias voltage is firstly applied to the needle tip to generate an emission current having a current value in an order of microamperes, then the negative bias voltage is maintained for a preset duration or is adjusted until an emission current of a predetermined value is generated, and thereafter the negative bias voltage is adjusted such that the electron source emits a current of an order of less than mA, so as to avoid the needle tip from being changed in terms of a morphology or burnt-out; and/or in a case where a positive bias voltage is applied to the needle tip for forming the emission sites, the positive bias voltage is applied to the needle tip for a preset duration, the positive bias voltage having a value less than a value of a bias voltage for field evaporation for forming a protrusion; and wherein for the positive bias voltage applied, a resulting field strength is in a range from 1 V/nm to 50 V/nm; or for the negative bias voltage applied, the resulting field strength is in a range from 1 V/nm to 30 V/nm. forming one or more fixed emission sites on a needle tip, the emission sites including a reaction product formed by metal atoms on a surface of the needle tip and gas molecules under an electric field, the emission sites are rooted on the surface of the tip, rather than dissociative on the surface of the tip, since the emission sites are the reaction product formed by metal atoms fixed on the surface and the gas molecules; wherein the gas molecules include hydrogen-containing gas molecules, or hydrogen-containing gas molecules and any one or more of the following: nitrogen-containing gas molecules, carbon-containing gas molecules or oxygen-containing gas molecules, wherein a material of the metal atoms comprises one or more of: tungsten, tantalum, niobium, molybdenum, rhenium, hafnium, iridium, osmium, rhodium, ruthenium, platinum, palladium, gold, chromium, vanadium, zirconium, titanium, and metal-hexaboride, wherein a temperature of the needle tip is lower than or equal to 1, 000K, and a pressure is less than or equal to 10 -3 Pa; wherein the electric field is obtained by applying a bias voltage; wherein the applying a bias voltage includes any one or more of the following: applying a positive bias voltage, applying a negative bias voltage, or a combination of applying a positive bias voltage and applying a negative bias voltage, in a case where a negative bias voltage is applied for forming the emission site, the negative bias voltage is firstly applied to the needle tip to generate an emission current having a current value in an order of microamperes, then the negative bias voltage is maintained for a preset duration or is adjusted until an emission current of a predetermined value is generated, and thereafter the negative bias voltage is adjusted such that the electron source emits a current of an order of less than mA, so as to avoid the needle tip from being changed in terms of a morphology or burnt-out; and/or in a case where a positive bias voltage is applied to the needle tip for forming the emission sites, the positive bias voltage is applied to the needle tip for a preset duration, the positive bias voltage having a value less than a value of a bias voltage for field evaporation for forming a protrusion; and wherein for the positive bias voltage applied, a resulting field strength is in a range from 1 V/nm to 50 V/nm; or for the negative bias voltage applied, the resulting field strength is in a range from 1 V/nm to 30 V/nm.