Ultrafast changes of reflection and transmission were measured simultaneously for Ta2O6 single layer on fused silica substrate under excitation of femtosecond laser pulses. Peak modifications of -3.4% for index of refraction and 0.042 for extinction coefficient were retrieved respectively by a model of single absorption layer on transparent substrate. The maxinia of changes emerged about 100 fs after the pump pulse, and then decayed with a time constant of about 600 fs.