The effect of pressure on the conformational structure of amyloid &beta (1-40) peptide (Aβ(1-40)), exacerbated with or without temperature, was determined by Fourier transform infrared (FT-IR) microspectroscopy. The result indicates the shift of the maximum peak of amide I band of intact solid Aβ(1-40) from 1655 cm^-1 (α-helix) to 1647-1643 cm^-1 (random coil) with the increase of the mechanical pressure. A new peak at 1634 cm^-1 assigned to β-antiparallel sheet structure was also evident. Furthermore, the peak at 1540 cm^-1 also shifted to 1527 (1529) cm^-1 in amide II band. The former was assigned to the combination of α-helix and random coil structures, and the latter was due to β-sheet structure. Changes in the composition of each component in the deconvoluted and curve-fitted amide I band of the compressed Aβ(1-40) samples were obtained from 33% to 22% for α-helix/random coil structures and from 47% to 57% for β-sheet structure with the increase of pressure, respectively. This demonstrates that pressure might induce the conformational transition from α-helix to random coil and to β-sheet structure. The structural transformation of the compressed Aβ(1-40) samples was synergistically influenced by the combined effects of pressure and temperature. The thermal-induced formation of β-sheet structure was significantly dependent on the pressures applied. The smaller the pressure applied the faster the β-sheet structure transformed. The thermal-dependent transition temperatures of solid Aβ(1-40) prepared by different pressures were near 55-60 °C.