Nitrogen-vacancy (NV-) centers of diamond can realize the function of high-sensitivity physical quantity detection with superior photo-luminescence properties. The concentration of NV- centers is one of the main factors that affect the physical quantity detection sensitivity in the macro field. The paper studied and analyzed the relationship between different electron injection doses and the concentrations of NV- centers. The research method was carried out as follows: firstly, diamonds were exposed to electron irradiation and further subjected to high temperature annealing in vacuum in order to prepare NV- centers; then, a Raman spectrometer was utilized to test the fluorescence spectra of diamond in the following three stages: before and after electron irradiation, and after annealing, so that the Raman spectral characteristic of diamond was analyzed during the NV- center preparation process; finally, the concentrations of the prepared NV- centers were estimated, and the influence rules of different electron injection doses on the concentrations of the NV- centers were also explored. The results show that after electron injection is performed on diamond, luminescence defects of 524.7, 541.1, 578 and 648.1 nm are formed, wherein centers of 524.7 nm are commonly found in HPHT synthetic diamond subjected to electron injection. After annealing at high temperature (≥800 ℃) in vacuum (≥10-7 Pa) is performed on diamond subjected to electron injection, vacancies move freely, the unstable defects disappear, and nitrogen-vacancy centers are formed when the vacancies are bound while moving close to nitrogen atoms. For diamond with a nitrogen content of 100 ppm, the relationship between the concentrations of NV- centers and the electron injection dose was in line with Boltzmann distribution when the number of vacancies produced with electron injection is smaller than 120 ppm (2.1×1019 cm-3). This study provides a reference basis for quantitative preparation of NV- centers by utilizing diamond with the nitrogen content of 100 ppm, and further lays a foundation for application of NV- centers to precision macroscopic physical quantity measurement.