Recently, graphene-based nanomaterials have attracted widespread attention as new electrode-modified materials for different electrochemical sensing platforms. However, graphene-based nanomaterials modified heavy metal sensors often have the disadvantages in that their detection ranges are not wide enough. To solve this problem, an easy and feasible approach derived from laser engraving technique to fabricate a high-quality 3D porous graphene-based heavy metal sensor with a quite wide detection range was established. The nitrogen-doped laser engraved graphene (N@LEG) was synthesized via introducing polyaniline (PANI) and polyvinylpyrrolidone (PVP) as N-dopant. Herein, by coupling the unique electrochemical properties and the 3D porous structure framework with large electrochemical active surface areas of LEG with the strong metal ions affinity of N atoms, N@LEG modified glassy carbon electrode (N@LEG/GCE) with in-situ bismuth film modification has been successfully utilized for the simultaneous determination of Cd(II) and Pb(II) using square wave anodic stripping voltammetry (SWASV). After optimizing conditions, the proposed sensor exhibits quite wide linear ranges varying from 5 to 10 g L−1 and 10 to 380 g L−1 for Cd(II), and 0.5 to 10 μg L−1 and 10 μg L−1 to 380 μg L−1 for Pb(II), respectively. In addition, the detection limits are calculated to be 1.08 g L−1 (S/N = 3) for Cd(II) and 0.16 g L−1 (S/N = 3) for Pb(II), which are nearly 3 times and 60 times less than the guideline values of the drinking water presented by the World Health Organization (WHO), for Cd(II) and Pb(II), respectively. Furthermore, the results describe satisfactory advantages of remarkable sensitivity, selectivity, anti-interference, repeatability, reproducibility and stability. Besides, the fabricated sensor is proved to be a potential perspective to detect Cd(II) and Pb(II) in actual water samples.