A novel synthesis method on solvent-free reaction using improved jet milling was described. Synthesis of a schiff base derived from p-hydroxybenzaldehyde and p-aminobenzoic acid had been achieved by solvent-free reaction using improved jet milling, and the structure of the compound have been characterized by Fourier transform infrared spectrometer, 1H nuclear magnetic resonance techniques and mass spectrometry. Differential thermal analysis of reaction process shown that the reaction was complete within 6 min. The scanning electron microscopy shown that the particles of the schiff base were regular and the size of the most particles was 0.5~1 μm. At the same time, the theoretical analysis about reaction process of solvent-free reaction using improved jet milling was preliminary studied. This solvent-free reaction using improved jet milling not only involves mild conditions, a simple operation and short reaction time, but also gives quantitative yield without waste producing work-up procedures. Simultaneously, the investigation also showed this reaction method was feasible, and of benefit to environment.