The invention designs novel 18F labeled p-nitro benzoyl amino acid derivatives. The derivatives are characterized in that one end of the derivatives is provided with 2-fluorine 18-4-nitro benzoyl structure, and the other end of the derivatives is provided with alpha-amino acid derivative structure (derived group R2 is methoxyl group, methylamino group and N,N-dimethylamino group respectively); and substituent R1 is positioned on an alpha site of carbonyl group and is hydrogen, methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, benzyl group, 2-methylthio-ethyl group, carboxyethyl group, carboxypropyl group, phenyl or imidazole methyl group. The structures at two ends are directly connected through amido bond. The structure of the derivatives is shown in a formula A. The compounds are simple to synthesize, fast to label, large in the amount of initial absorption and slow to clear in tumor tissue, low in uptake or fast to clear in other normal tissue and blood and high in degree of distinguishing tumor from background. The invention also relates to the application of the compounds serving as a PET brain tumor imaging agent. R2=OMe, HNCH3.