Based on holographic optical holographic imaging theory,a wavelength beam combining approach of fiber coupling lasers using off-axial holographic optical elements is proposed in this paper. This method for beam combining is easy constructed and high efficiency. This paper designs the off-axis holographic optical element (HOE),and gives the phase distribution of the element. We use the stimulation software Zemax and angular spectrum theory to calculate the combined beam divergence angle and the beam quality. The stimulation shows that for fiber lasers with wavelength at 635,808,975 nm,maximum M2 increases from 23.5 to 47.9 and the theoretical efficiency is 95%.