In this thesis, we have prepared bismuth selenide thin films which were grown on Sapphire(0001) substrates by pulsed laser deposition(PLD) and change various substrate temperature to get optimization. The surface morphology of samples with various substrate temperature was studied by means of Scanning Electron Microscopy (SEM).The crystal structure and carrier concentration were investigated by means of X-Ray Diffraction (XRD) and Hall measurement.The ultrafast carrier dynamics behavior have been studied by Optical Pump-Probe measurement (OPOP) . We use coherent optical phonon、coherent acoustic phonon to anlyze high frequency and low frequencyΔR/R singnal then find the appearance of Bi-rich condition on thin film surface.