The invention discloses a sealing device for a drive mechanism of a horizontal centrifuge, which can prevent foreign liquid from entering an oil tank and recover a small amount of lubricating oil, and comprises a bearing seat arranged on a rack, a bearing arranged in the bearing seat and a gland arranged at the outer side of the bearing, wherein the bearing seat is internally provided with an oilreturning slot; a main shaft is arranged in the bearing in a penetrating way and penetrates through the gland; a sealing case is arranged between the gland and the main shaft; a main baffle ring is arranged at the inner side of the sealing case; a leakage-proof ring and at least two subsidiary baffle rings are arranged on the inner wall of the gland; the leakage-proof ring is arranged at the outermost part; gaps are respectively arranged between the main baffle ring and the gland, the leakage-proof ring and the sealing case, and the subsidiary baffle rings and the sealing case; a liquid stopping trough is formed between the leakage-proof ring and the adjacent subsidiary baffle ring thereof; the liquid stopping trough is communicated with the liquid returning slot arranged at the outer side of the gland; an oil stopping groove is formed between two adjacent subsidiary baffle rings; and the oil stopping groove is communicated with the oil returning slot by an oil returning channel arranged at the inner side of the gland. The sealing device is mainly used in a high-speed horizontal centrifuge.