The invention discloses a butyl phthalide medicinal composite, which comprises butyl phthalide and silicon dioxide according to a mass ratio of 0.1-4:1. The preparation method comprises the following steps: weighing butyl phthalide and silicon dioxide, spraying butyl phthalide into silicon dioxide powder, and evenly mixing to obtain the powdery butyl phthalide medicinal composite. At the same time, the invention also discloses a sustained-release preparation of the butyl phthalide medicinal composite. The sustained-release preparation is characterized in that the butyl phthalide medicinal composite is taken as the active component, which is wrapped by one or more pharmaceutically-acceptable sustained-release coating materials. The preparation method is simple, the preparation time is short, the cost is low, and the preparation method is economic. The prepared medicinal composite has the advantages that the drug volatilization is effectively controlled, the stability is high, the drug loading capacity is large, the volume is small, and the dosage form is convenient for oral taking. The shortages of conventional commercial oral butyl phthalide preparations in clinic are overcome.