NOVELTY - Preparation of levetiracetam involves ultrasonically reacting (pts.wt.) 2-aminobutanamide hydrochloride (100) and acetonitrile (900); adding 250 pts.wt. anhydrous potassium carbonate; stirring for 10 minutes; adding 125 pts.wt. 4-chlorobutyl acyl chloride; reacting at 30 degrees C for 20 minutes; filtering; decompressing and drying to obtain intermediate A; ultrasonically reacting (pts.wt.) intermediate A (100) and methylene dichloride (1200); stirring; and reducing temperature at 2 degrees C.    USE - Preparation of levetiracetam.    ADVANTAGE - The method improves product yield, shortens production period, reduces cost, improves operation condition, and is environment friendly.    DETAILED DESCRIPTION - Preparation of levetiracetam comprises reacting (pts.wt.) 2-aminobutanamide hydrochloride (100) and acetonitrile (900) in ultrasonic microwave chemical reactor at ultrasonic frequency of 20-30 kHz and microwave frequency of 2450 MHz; adding 250 pts.wt. anhydrous potassium carbonate; stirring for 10 minutes; adding 125 pts.wt. 4-chlorobutyl acyl chloride; reacting at 30 degrees C for 20 minutes; filtering at 40 degrees C; decompressing and drying to obtain intermediate A; putting (pts.wt.) intermediate A (100) and methylene dichloride (1200) in ultrasonic microwave chemical reactor; stirring; reducing temperature at 2 degrees C; adding (pts.wt.) tetrabutyl ammonium bromide (8), anhydrous sodium sulfate (80), and potassium hydroxide (30); stirring and reacting for 1 hour; heating at room temperature under ultrasonic frequency of 20-30 kHz and microwave frequency is 2450 MHz for 20 minutes; filtering at 50 degrees C; decompressing and removing solvent to obtain oily matter; adding 300 pts.wt. ethyl acetate; stirring; separating out crystal; filtering; decompressing and drying at 50 degrees C to obtain crude product; adding 500 pts.wt. ethyl acetate; heating and refluxing; adding 2 pts.wt. active carbon to decolor; filtering; adding into ultrasonic microwave chemical reactor with ultrasonic frequency of 40 kHz; refluxing for 5 minutes; and drying in spray dryer at 30-50 degrees C, 0.02-0.04 MPa, and flow speed of 450-650 m/s to obtain nano levetiracetam product.