The rapidly quenched La80Al20 alloy is amorphous. At atmospheric pressure, its crystallization temperature and glass temperature are ～280℃ and ～242℃ respec-tivily, according to DTA measurements. The superconducting transition temperature Tc increases from 3.87 to 4.18K, in the hydrostatic pressure range of 1-4770 bars, while its residual resistance decreases significantly. After high pressure-high temperature treatment (25kbar, ～160℃, 40 min), amorphous→crystalline transition of La80Al20 alloy occurs, as disclosed by X-ray diffraction method. The product consists of α-La phase and a new metastable phase, and its Tc increases from 3.9 to 5.7 K. Some preliminary discussion on the experimental results are also presented.