Two electrochemical signals of the MCF-7 cell were simultaneously detected by using multiwall carbon nanotubes and room temperature ionic liquid composite film modified electrode. The signal at +0.726 V due to the oxidation of xanthine and guanine, was obviously improved. And the signal at +1.053 V due to the oxidation of hypoxanthine and adenine was found for the first time. This two-signal electrochemical method is credible to detect cell viability and proliferation.