The electrochemical sensor is constructed based on porous reduced graphene oxide (PrGO), carboxymethyl cellulose (CMC) and fondaparinux (Fonda) nanocomposite modified glassy carbon electrode (GCE) and it was applied for the simultaneous trace detection of Cd2+ and Pb2+ by SWASV. Experimental parameters, such as the deposition time, deposition potential, effect of supporting electrolytes and its pH values were optimized. Under the suitable conditions, the current responses are increased linearly with a concentration range from 2 to 20 nM. The achieved detection limits (LOD) are 0.28 and 0.17 nM for Cd2+ and Pb2+ respectively, at a signal to noise ratio 3. The sensitivity obtained for the PrGO/CMC/Fonda/GC electrode was 2.7 mu A/nM (Cd2+) and 2.9 mu A/nM (Pb2+). The proposed electrode demonstrated good stability, selectivity, reproducibility (RSD = 2.7% (Cd2+) & 2.86% (Pb2+)) and high sensitivity. Finally the PrGO/CMC/Fonda/GC electrode was successfully utilized for the simultaneous sensitive detection of Cd2+ and Pb2+ in ground and sewage waters and gave satisfactory result (the relative error was lower 0.7%).