An original electrochemiluminescent (ECL) luminophore porphyrin nanosphere–graphene oxide composite (TCPP NS-GO) was prepared. The TCPP NS-GO could produce greatly enhanced ECL in buffer with potassium peroxydisulfate (K2S2O8) as the co-reactant. The enhancement ECL mechanism of TCPP NS-GO/K2S2O8 system was investigated in detail. Moreover, The TCPP NS-GO composite had an abundant surface functional group to expand its application, which exhibited high sensitivity and selectivity to Fe3+. The wide linear relationship between ECL intensity and Fe3+ concentration from 0.002 to 5.128μmolL−1 (R2=0.998) was found with the detection limit as low as 1nmolL−1. The ECL quenching mechanism of Fe3+ was proved by UV-vis absorption spectroscopy, Fluorescence emission spectroscopy (FL) and Fourier transform infrared spectroscopy (FT-IR) analysis technology.