A novel diamine monomer, 4-[4-(1-pyrrolidinyl)phenyl]-2,6-bis(4-aminophenyl) pyridine (PPAP), was synthesized using 4-(1-pyrrolidinyl)benzaldehyde as starting material, and a series of aromatic polyimides were prepared using PPAP and five aromatic dianhydrides by a two-step imidization method. The structure and properties of as-prepared polyimides were studied by Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance (NMR), thermogravimetric analysis (TG), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD). The results indicated that these polymers had good solubility in highboiling organic solvents upon heating, such as N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and N-methyl-2-pyrrolidone (NMP). Furthermore, they had outstanding thermal properties with the glass transition temperature (Tg) exceeding 354 oC, as well as T5% and T10% mass loss temperature under a nitrogen atmosphere in the range of 521~534 oC and 544~594 oC, respectively. Moreover, they exhibited excellent hydrophobic properties with the contact angles ranging from 82.7 to 90.5°. In addition, the results of WAXD showed that these polyimides exhibited the structure of amorphous polymers.