The invention discloses a preparation method and product of a swine fever live vaccine. The preparation method comprises the following steps: (1) culturing a swine-derived continuous cell line; (2) inoculating the swine-derived continuous cell line into a seed virus for producing the swine fever live vaccine, thereby obtaining a swine fever weak-virus vaccine strain; (3) carrying out virus multiplication on the swine fever weak-virus vaccine strain; (4) determining the virus value of the multiplied virus suspension by an immunofluorescence method; and (5) adding a freeze-drying protective agent and antibiotics into the qualified virus suspension to carry out vaccine preparation and freeze-drying. Since the swine fever live vaccine is prepared from the cell line, the difference of quality among different batches is small, and the invention has the characteristics of simple and stable technique, high yield, low cost and the like, is easy to operate, and has feasibility and amplification of industrialized mass production. In addition, the immunofluorescence method, which has the advantages of high detection sensitivity, high speed, high specificity, high accuracy, high repetitiveness and reliable result, is used for determining the virus value of the multiplied virus suspension. The swine fever live vaccine disclosed by the invention can 100% protect the attack of swine fever strong virus.