A laser system design is presented for an absolute gravimeter based on 87Rb atom interferometer. By skillful design, lasers with 9 kinds of different frequency are based on two diode lasers including tapered amplifier. Two electrical feedback systems are used for laser frequency stabilization and generating the Raman lasers, respectively. All other lasers are based on two Raman lasers and realized with frequency shifting by acoustic optical modulators. This laser system not only has the compact and simple construction, but meets all the requirements for laser power and frequency controlling. It has the characteristic of reliability and integrity.