Pearcey beam was obtained by designing a simple optical element-parabolic slit aperture. Based on the generalized Huygens-Fresnel diffraction integral in the spatial domain, the Pearcey beam expression of the system was derived. Numerical simulations and experiments verify the generation of Pearcey beams. At the same time, the self-focusing characteristics of the Pearcey beam were studied, and the effect of the focal distance of parabolic silt aperture on the focal spot was discussed. The experimental results show that the size of the self-focucal spot was consistent with the numerical simulation. The results provide theoretical and experimental basis for the Pearcey beam for optical trapping.