The characteristics of the temporal spectrum of optical scintillation in a finite aperture in the turbulent atmosphere are analyzed theoretically. Experiments of laser scintillation in a pinhole and a 260 mm aperture were carried out along a 6.8 km propagation path. Comparisons of scintillation spectra and standard deviations are made between those for the pinhole and the 260 mm aperture. It can be concluded that the aperture averaging can be saturation-resistant for the saturation to some extent. This provides a foundation for measuring optical turbulence intensity using scintillation in a finite aperture.