We systematically study ultraviolet laser-induced ultrafast photovoltaic effect in miscut $\mathrm{La}\mathrm{Sr}\mathrm{Al}{\mathrm{O}}_4$ single crystal wafers with different thicknesses at ambient temperature without any applied bias. An open- circuit photovoltage (PV) is obtained when the wafer is irradiated by a $248\mathrm{nm}$ laser pulse of $20\mathrm{ns}$ duration. With the decrease of crystal thickness, the peak PV increased to a maximum of $2.66\mathrm{mV}$ at $340\mathrm{\mu m}$ and then decreased to $1.3\mathrm{mV}$ at $155\mathrm{\mu m}$ . Meanwhile, the 10%–90% rise time of photovoltaic responses declines gradually. The inner mechanism of the present thickness-dependent photovoltaic response is discussed.