Wigner distribution as a function expressing signal in space and frequency field simultaneously, is caused an extensively interest in the world. But up to now, the main methods reported to obtain the Wigner distribution of 2D signals are through optical ways. The discrete numerical methods reported to obtain Wigner distribution is only limited to one dimension, for the Wigner distribution of 2D signals contain 4D variables (2D space variables and 2D frequency variables), its calculation is intricate, and till now, there is no report of this aspect. In this paper, the discrete calculation method of Wigner distribution for 2D signals is put forward, and the Wigner distributions of 2D real signals (a circle aperture, a ring aperture and a rectangle aperture) are simulated.