The digital speckle fringe pattern is modulated by spatial carrier in large-shearing electronic speckle pattern interferometry (ESPI). The carrier is introduced by rotating the reference plane a small angle. When Fourier transform is used to demodulate the modulated fringe pattern, the phase of deformation is calculated and furthermore the deformation is measured accurately. The principle of carrier modulation in large-shearing ESPI is discussed. The theoretical analysis shows that the frequency of carrier used for modulation is proportional to the rotational angles of reference plane. Therefore, the fringe patterns with different displacements can be modulated easily by rotating reference plane different angles. A typical experiment using a centrally loaded clamped circular plate is completed. The experimental results prove that the carrier introduced by rotating the reference plane in large-shearing ESPI can modulate speckle pattern very well and the displacement fields can be obtained effectively. The optical modulation system has some advantages: the system is simple and has no special reference beam for interference. And the carrier pattern has higher fringe visibility. This technique presented here would extend the application range of ESPI and have some applications in practices.