The mechanism of laser peening forming was analyzed and the precision of laser peening forming was tested by experiments. In the experiments, the parameters of Nd: Glass laser were as following: the wavelength 1.06μm, the pulse duration 23 ns, the output power 32 J. The material of sample was aeronautic aluminum alloy LY12CZ, and its size was 150mm×90mm×3.5mm. The sample surface was coated with black paint and flowing water curtain served as overlay. The curvature radius of pre-bending die was 500mm. The shape of deformed plate after laser peening was measured. The experimental data indicate that the curvature radius of specimen after laser peening under elastic pre-bending state is 1872.13mm, and the maximum difference value in the R direction is 0.79mm. Comparing with the traditional forming processes, it is a high-precision forming technology.