Technique of combining time- average digital holography with digital imaging to measure the amplitude field of object is proposed, the imaging lens is introduced into the optical system of time- average digital holography, and the vibration of large objects can be analyzed by time- average digital holographic technique. The basic theory of this technique is described, the related optical system is designed, and the results are verified by experiments with the help of a round piezoelectric ceramic piece.These experiments show that the digital holographic interferogram recorded and reconstructed by digital imaging time- average holographic technique agree well with that recorded and reconstructed by traditional time- average holographic interferometry under identical condition. Error of amplitudes of both obtained by calculating through comparisons is very small.