The method for retrieving a similar sentence to a source sentence inputted by a user through a translation memory in a translation aid system is provided. An inverted file of an index word and a translation memory from a parallel corpus are constituted. Candidate sentences having a high similarity are filtered by comparing the source sentence provided by the user with sentences of the constituted translation memory. A source sentence and a corresponding target sentence are outputted in the order of similarity by calculating similarity between the filtered candidate sentences and the source sentence.