In this report, we described the electrochemical preparation and the electrical characterization of a novel composite layers formed by graphene (Gr) and poly(1,8-diaminonaphthalene) conducting polymer - p(1,8-DAN). The p(1,8-DAN) has amino and/or imino groups which capable of chelate complexation with Hg2+ ions in aqueous solution. Thanks to the sensitive interface of Gr/p(1,8-DAN) as well as the oxidizing characteristics of (Hg2+/Hg22+) redox couple, the square wave anodic stripping voltammetry could be recorded for the detection of Hg2+ with a well-defined peak at +0.63 V (vs. SCE). The Gr/p(1,8-DAN) composite film may offer a new type of sensing materials to be used for trace analysis of heavy metals ions.