The invention discloses a 3-cyanoaniline alkyl aryl piperazine derivative and application thereof in preparing medicaments. The 3-cyanoaniline alkyl aryl piperazine derivative disclosed by the invention has very useful pharmaceutical properties and excellent tolerance, and especially can be used as a novel analgesia, a novel antidepressant medicament, and a novel analgesic and antidepressant medicament. The compounds are 5-hydroxytryptamine regulated central analgesias, and also are 5-hydroxytryptamine regulated novel antidepressant medicaments. The compounds also are low in toxic and side effects and large in safety range. The 3-cyanoaniline alkyl aryl piperazine derivatives are compounds as shown in a formula (III), or free bases or salts thereof.