In the cold atom interferometer, the fluctuation of the number of trapped atoms will be transformed into the equivalent phase fluctuation of the interference signal, which will directly affect the measurement results. To solve this problem, the active stabilization technology for the number of trapped atoms in the cold atom interferometer is proposed in this paper. By measuring the number of atoms in the final state of interference and feedback controlling the loading time of 3D-MOT, the active stabilization of the number of trapped atoms has been realized. By applying this technology, when the loading time is about 40 ms, the short-term fluctuation of the number of atoms trapped in 3D-MOT is reduced from 27.1%@0.5 h to 7.4%@0.5 h, and the long-term drift is reduced from 39.9%@10 h to 10.4%@10 h, which significantly improves the stability of atom trapping. This technology can solve the problem of large fluctuation of the number of trapped atoms caused by the attitude change of the cold atom interferometer under dynamic conditions.