The factors of influencing the mass sensitivity distribution of quartz crystal microbalance (QCM) have been analyzed based on the mass sensitivity expression of QCM. A QCM immunosensor with novel electrode configuration has designed and simulated on a 9 MHz QCM. The simulation results show that the QCM mass sensitivity distribution of the novel electrode structure is more uniform than that of the circular electrode in the full electrode region.A 10 MHz modified electrode QCM immunosensor with high resonance quality factor Q is applied to detect the antibody of the NuTu 19 ovarian cancer cell from serum samples and the experimental results show that the frequency shifts of the quartz resonator are nearly linearly dependent on the amount of NuTu 19 antibody mass in the range of 74 to 370 ng, which show that the modified electrode configuration QCM immunosensor has good mass sensitivity distribution.