An electrochemical impedance method at a fixed frequency (10Hz) is used to detect folate receptor-rich cancer cells with the interaction between folic acid immobilized on gold nanoparticles deposited on boron-doped diamond (BDD) electrode surface and its receptor over-expressed on cancer cell membrane without additional labeling. Experimental results have shown that the BDD electrode modified with folic acid can clearly denote folate receptor-rich cancer cells, such as HeLa cells, at a concentration down to 10 cells mL(-1). The high sensitivity of BDD electrode is resulted from the change of field effect and surface charge density of BDD after cancer cells attachment. The BDD electrodes can be regenerated with 0.1M citric acid/glycine/HC1 at pH 3.0 and used seven times again. Therefore, electrochemical technique with BDD electrode has been introduced for cancer cells detection and a simple method to detect folate receptor-rich cancer cells without additional labeling has been developed.