Translation-Based Steganography (TBS) is a class of text steganography.When translating the same sentence from a natural language to another by different translators

there are normally different translation results.Making use of this property

TBS chooses from different translation results of a sentence according to secrete messages to generate stego-text.Because TBS basically preserves syntactic correctness and semantic coherence

it is comparatively difficulty for traditional detections to detect this method.Our research shows that there exists a detection method for TBS when we know the Machine Translation (MT) set that being used by TBS.So it is crucial important to keep a secret of the MT set.This paper theoretically analyzes the effective of our detection method and gives the detection process and experiment results.Additionally

we propose a method to improve the security of TBS.