The invention belongs to the technical field of centrifugal casting, and relates to a method for preventing crack defects in centrifugal casting of a small-caliber duplex stainless steel shaft sleeve. The rotating speed of a casting die is lowered when metal liquid is poured for manufacturing the small-caliber duplex stainless steel shaft sleeve, and the rotating speed of the casting die is made to meet the adjustment coefficient beta=0.85-0.90 in a Kostiantynivka formula; the rotating speed of the casting die is lowered again 25 seconds after the metal liquid is poured, and the rotating speed of the casting die is made to meet the adjustment coefficient beta=0.70-0.80 in the Kostiantynivka formula; meanwhile, when the metal liquid is poured for manufacturing the small-caliber duplex stainless steel shaft sleeve, the mass ratio of a casting and the casting die is made to be 0.3<=Mcasting/Mcasting die<=0.6. The method for preventing the crack defects in the centrifugal casting of the small-caliber duplex stainless steel shaft sleeve has the advantages that casting parameters, technological parameters and the like are taken as an organic whole, the matching relations among multiple parameters are emphasized, the situation of heat cracks generated in the centrifugal casting of the small-caliber duplex stainless steel shaft sleeve is improved obviously, the manufacturing cost of the product is reduced greatly, and production efficiency is improved.