Abstract: The author used ethylenedicystein as a bifunctional chelating agent and MDP as a medium chelating agent, applied two-step method to label EC-NGR-IFN-α2a with 99Tcm,and then, the bioactivities of EC-NGR-IFN-α2a and 99Tcm- EC-NGR-IFN-α2a were identified as well. It showed that the productivity of EC-NGR-IFN-α2a was 87%, the radiolabelling rate and the radio chemical purity (RCP)of 99Tcm- EC-NGR-IFN-α2a was 86%, 96% respectively; In vitro, the radiolabelled compound had good stability,no bioactivity difference was found among EC-NGR-IFN-α2a, 99Tcm-EC-IFN-α2a-NGR and IFN-α2a-NGR.