Purple sweet potato anthocyanin extraction process

The invention provides a purple sweet potato anthocyanin extraction process which includes the steps of 1), smashing purple sweet potatoes, adding acidified alcohol for reflex extraction to obtain a crude anthocyanin extract; 2), feeding the crude anthocyanin extract to HPD-300 type macroporous resin columns to collect effluent liquid, eluting the columns by means of hydrochloric acid until the columns become colorless, and then eluting the columns by acidified alcohol to collect alcohol eluent; 3), feeding the effluent liquid collected in the step 2) to AB-8 type microporous resin columns and eluting the columns by means of alcohol 80-95% in volume concentration to collect alcohol eluent; 4), mixing the alcohol eluents respectively collected in the step 2) and the step 3), concentrating the alcohol eluents under vacuum to recover alcohol, and then freezing under vacuum to dry so as to obtain purple sweet potato anthocyanin powder. Purple sweet potato anthocyanins extracted by the process have stable property and high color value.