In order to control laser beams precisely in a caesium atom interferometer, a laser frequency and power control system which is suitable for various demands is designed. Based on an acousto-optical modulator, the system integrates the functions of frequency shift, power stabilization and modulation. Firstly, based on the principle of the atom interferometer, the requirement of the optical part in the system is proposed. Secondly, the hardware circuit system including a phase-locked loop frequency synthesizer and the LabVIEW software control system are designed. Finally, the developed system is tested. The experimental results show that the frequency shift range of the laser beam through the acousto-optical modulator is 100~200MHz;and the power fluctuation of the laser decrease to 2% using the power stabilization system. The designed system has multi-functions, achieves the desired aims and satisfies the requirements of atom transition, matter wave interference and other processes to laser beams. In addition, the designed system could be applied to other systems which need to adjust and control laser beam precisely, such as atomic clock, atom interferometer gravity gradiometer and so on.