SiO2 colloidal crystal template was fabricated by the solvent vaporization convection self-assembly method. The low pressure chemical vapor deposition method was then used to fill the voids of the silica colloidal crystal template with high refractive index silicon, thus silicon inverse opal photonic crystal was obtained. The modality structure silicon inverse opal was characterized by scanning electron microscopy. Its photonic bandgap structure was calculated based on plane wave expansion method. Its photonic bandgap properties were characterized by Fourier transform infrared spectroscopy. The results showed that silicon is homogeneously distributed inside the voids of silica template. The wavelength and bandwidth of photonic bandgap measured by microscopic infrared spectrometer agree with the calculated one. The tilt-angle reflectance spectra along the different incidence angles showed that the refection peaks with the band center wavelength of 3319 nm always existed. This result proved that silicon inverse opal has the complete photonic bandgap. The bandgap lies in the range of mid infrared atmosphere window.