The effect of pressure annealing on the glass transition of bulk amorphous Zr55Cu30Al10Ni5 is studied by x-ray diffraction and differential scanning calorimeter (DSC). The apparent activation energy of the glass transition (Eg) was determined by the Kissinger method. The results show that the glass transition temperature and Eg of the specimens change nonlinearly with increase of the annealing pressure. The role of pressure on structural relaxation and the glass transition is discussed.