Aiming at the problem of white noise amplification of differential microphone array, a design method of parametric differential beamformer was proposed. Through theoretical derivation, it is proved that the delay summing beamformers can maximize the white noise gain and the superdirected beamformers can maximize the directional gain. The orthogonal eigenvector was obtained by using the unitary diagonalization method to deal with the pseudo-correlation matrix between the steering vector and the white noise gain, and the parameters of the beamformer machine were designed based on it. Through simulation experiments, the performance of parametric differential beamformers under different parameter settings was analyzed. Experimental results show that the proposed method can flexibly balance and adjust the white noise gain and directional gain by adjusting the parameters.