With the help of questionnaires,logical ability tests,translation tests and interviews,the experiment conducted in this paper studied sixty CATTI Level-2 test-takers with equal English proficiency,probing into the effects of their logical ability in understanding Chinese language on their translation competence.The findings are as the following:translators' logical ability in understanding Chinese significantly correlates to their translation competence and to the anticipated quality of their translation,which indicates that translators with a high level of English proficiency should pay more attention to the development of their logical thinking ability in understanding the Chinese language,their mother tongue,as it greatly affects their translation competence.