Abstract: To understand laser induced damage mechanism of optics, the damage dynamics of fused silica induced by ultraviolet picosecond laser is investigated using shadow graphic and laser-deflection imaging technique and photoelectric detection technique. The results show that shock/pressure wave propagation, transient absorption and crack propagation evolve during ultraviolet picosecond laser irradiation. The speed of propagation of shock/pressure wave is about 6.9 μm/ns. The transient absorption of damage region remains absorbing until 50 μs. The maximum absorption is reached 2.5 μs delay. The cracks stop growing at the 7.5 ns delay.