The experimental investigation of the fiber Bragg grating (FBG) sensor in monitoring action for the laser thrombolysis is introduced. In laser thrombolysis, the pulsed laser is absorbed by blood, leading to cavitating bubbles. The shock wave is generated during bubble expansion and collapse. With a tunable distributed feed back (DFB) LD laser as the light source and an edge filtering demodulation, the shock wave was measured by FBG based sensing system. In experiment, the peak power of the shock wave response increases with the laser power, and the FBG responsibility for the shock wave in the blood after ablation of clot is similar to that in blood without clot. According to this similarity, whether the clot is ablated or not can be distinguished. In the in vitro experiment, the measured ablation time is 23 s.