The invention discloses a novel application of lauromacrogol in preparing a medicament for treating sublingual gland cyst, belonging to novel applications of old medicaments. When a patient with both mouth floor venous malformation and the sublingual gland cyst is treated, the lauromacrogol is locally injected for treating the venous malformation, and the sublingual gland cyst is accidently found to be also cured, so that lauromacrogol injection therapy is carried out on multiple patients simply with the sublingual gland cyst immediately, and the patients are observed and found to be all cured. Therefore, the medicament for treating the sublingual gland cyst can be prepared from the lauromacrogol as a raw material. While, with adoption of the lauromacrogol for therapy, injection time is small, curative effect is good, and adverse reaction does not exist.