A preparation method of the crystal form I of the racemate of 4-hydroxy-2-oxo-1-pyrrolidine acetamide (oxiracetam) comprising the following steps:. dissolving crude oxiracetam in isopropyl alcohol to reach supersaturation;. heating and stirring for 7h at 38-42 °C to obtain a suspended sediment;. filtering and drying to obtain a crystal; wherein said crystal form I has diffraction peaks appearing at the following 2θ diffraction angles: 12.011, 15.318, 17.407, 19.633, 21.228, 22.052, 24.577, 25.223, 27.647, 28.161, 29.109, 30.805, 31.276, 31.766, 32.77, 33.477, 35.252, 35.645, 36.236, 37.379, 39.56, 40.489, 41.256, 41.948, 43.443 and 44.628; wherein said crude oxiracetam is synthesized by the following steps: (a) 139.6g of glycine ethyl ester hydrochloride was added to 1100mL of anhydrous ether, cooled to -6°C, and then 27.2g ammonia gas was introduced to form free glycine ethyl ester from glycine ethyl ester hydrochloride, wherein glycine ethyl ester hydrochloride: anhydrous ether: ammonia gas = 1mol:1100mL: 1.6mol; (b) to the above mixture 336mL of anhydrous alcohol and 67.2g of sodium bicarbonate were added, followed by the addition of 166.6g of ethyl 4-chloro-3-hydroxybutyrate in drops; the period for the addition in drops lasted for a time of 1.8h, then the reaction continued for 22h at a temperature of 72 °C and pH=8; (c) the above reaction solution was filtered, and the residue was fully washed with ethanol and the filtrate was concentrated; the concentrate was dissolved in water, and extracted by adding ethyl acetate 7 times to the weight of the filtrate; the aqueous phase was concentrated, and separated with column chromatography; finally, aqueous ammonia of 23 wt % was added and then the reaction continued for 4h at 22 °C to obtain crude oxiracetam, wherein the amount of 23wt% aqueous ammonia is 13 times to the weight of the product separated by column chromatography; wherein glycine ethyl ester: sodium bicarbonate: ethyl 4-chloro-3-hydroxybutyrate = 1: 0.8: 1 in moles, the amount of anhydrous alcohol is 5 times to the weight of sodium bicarbonate; (d) the crude product obtained above was dissolved in water, treated by 732 # strong acid cation exchange resin, and then neutralized with 711 # strong base anion exchange resin; the solution was collected and concentrated; wherein the crude product: water = 1g: 0.5mL, the crude product: the strong acid cation exchange resin = 1g: 10mL.. dissolving crude oxiracetam in isopropyl alcohol to reach supersaturation;. heating and stirring for 7h at 38-42 °C to obtain a suspended sediment;. filtering and drying to obtain a crystal; (a) 139.6g of glycine ethyl ester hydrochloride was added to 1100mL of anhydrous ether, cooled to -6°C, and then 27.2g ammonia gas was introduced to form free glycine ethyl ester from glycine ethyl ester hydrochloride, wherein glycine ethyl ester hydrochloride: anhydrous ether: ammonia gas = 1mol:1100mL: 1.6mol; (b) to the above mixture 336mL of anhydrous alcohol and 67.2g of sodium bicarbonate were added, followed by the addition of 166.6g of ethyl 4-chloro-3-hydroxybutyrate in drops; the period for the addition in drops lasted for a time of 1.8h, then the reaction continued for 22h at a temperature of 72 °C and pH=8; (c) the above reaction solution was filtered, and the residue was fully washed with ethanol and the filtrate was concentrated; the concentrate was dissolved in water, and extracted by adding ethyl acetate 7 times to the weight of the filtrate; the aqueous phase was concentrated, and separated with column chromatography; finally, aqueous ammonia of 23 wt % was added and then the reaction continued for 4h at 22 °C to obtain crude oxiracetam, wherein the amount of 23wt% aqueous ammonia is 13 times to the weight of the product separated by column chromatography; wherein glycine ethyl ester: sodium bicarbonate: ethyl 4-chloro-3-hydroxybutyrate = 1: 0.8: 1 in moles, the amount of anhydrous alcohol is 5 times to the weight of sodium bicarbonate; (d) the crude product obtained above was dissolved in water, treated by 732 # strong acid cation exchange resin, and then neutralized with 711 # strong base anion exchange resin; the solution was collected and concentrated; wherein the crude product: water = 1g: 0.5mL, the crude product: the strong acid cation exchange resin = 1g: 10mL.