The solution of piperine in multiple solvent including ethanol, acetic acid, water and HCl were investigated to extract more piperine from piper fruit. Piperine was determined by reverse phase high-performance liquid chromatography with Diamonsil column (C18,5 μm ,250 mm×4. 6 mm) at 343 nm. Experiment data were simulated by Allometric model and the formula is Z=0.9+ 4.54×10-10×x5.675+1.8029×y2.12848+2.37×10-10×x5.675×y2.12848(Z:sample solution,mol/mL,x: the percentage of ethanol’s volume, ml/100mL,y: the acetic acid in the authentic sample solution, g/100mL), the adj·R2=0.997, the comparative deviation less than 2%. These results are good in agreement with experimental data. It reveals that the model can meet the requirements of the selection and design in extracting piperine from piper fruit.