The influence on the measured vibration signal caused by the frequency-stability and signal power of driver signal to acousto-optic frequency shifter (AOFS) in the high-precision heterodyne laser doppler vibrometry (HLDV) with one AOFSs was analyzed. In order to reduce the frequency drifting and the phase noise of the driver signal, the HLDV composed with two AOFSs was proposed. And based on the direct digital frequency synthesis (DDS) technology, the design of the driving signal generation unit has been completed with AD9912 which has the characteristic of adjustable initial-phase and low phase noise. The vibration-measuring experiments performed with HLDV consists of two AOFS shows that the designed generation unit is able to drive the AOFS. Meantime, compared with the HLDV with one AOFS, the noise floor from 0 to 10 kHz of the HLDV with two AOFS is flat and the noise distribution below 1 kHz has been depressed greatly.