Method for refining carbidopa

The invention discloses a method for refining carbidopa, which comprises the following steps: diluting a crude carbidopa product with water, regulating the pH value to below 6.5 with acid, and heating to 50-110 DEG C under the nitrogen protection or/and reducer addition condition, thereby obtaining a crude product system; adding a decolorant into the crude product system to decolorize at 50-110 DEG C for 5-60 minutes; after decolorizing, filtering while the crude product system is hot to obtain a filtrate, stirring and cooling the filtrate to 0-30 DEG C, and continuing stirring at 0-30 DEG C for 0.5-5 hours to obtain a refined system; and filtering the refined system, washing the filter cake with water, and carrying out vacuum drying to obtain the finished carbidopa product. The method disclosed by the invention has the advantages of simple preparation method, favorable controllability, strong operability, high methyldopa (impurity) removal rate, high yield and low production cost, can easily implement industrial production, has high economic benefit in the industrial production, can be easily popularized, and has wide application prospects.