The diamond Nitrogen Vacancy (NV) center has been widely studied as a high-sensitivity magnetometer and has been used in many fields. In order to solve the problems of low fluorescence signal contrast and limited magnetic detection sensitivity, the traditional measurement method only uses a single axial NV centers for excitation and detection, a full - axis excitation method of dual - frequency microwave is used in this paper. Two pairs of resonant peaks are presented in the optical detection magnetic resonance spectrum by the bias magnetic field of a specific [111] crystal direction, and the corresponding dual-frequency microwave is superimposed to achieve synchronous regulation. After experimental verification, the fluorescence contrast of the derived rabbi oscillation signal and spin echo signal is increased by 2.83 times and 3.81 times compared with the uniaxial signal, respectively, and the ultimate magnetic noise sensitivity of the final system is increased by about 14.3 times to 0.76nT/√Hz. Finally, it is proved that full axis excitation is feasible to improve the magnetic sensitivity of the system.