The invention relates to a production method of pharmaceutical-grade ferrous sulfate, which comprises the following steps: adding feed-grade ferrous sulfate to a sulfuric acid solution while mixing, dissolving the feed-grade ferrous sulfate; raising the temperature, adding industrial grade reduction iron powder, raising the temperature again, stirring for a period of time, and adjusting the pH value by sulfuric acid or iron powder; filtering; reducing the temperature to crystallize and separate out ferrous sulfate; centrifugally dehydrating; and drying. The production method has the characteristic of being suitable for industrial production, belonging to the technical filed of the pharmaceutical technology; and the pharmaceutical-grade ferrous sulfate prepared by the method of the invention has high purity and reliable quality.