Using an efficient, full-vectorial numerical simulation method, we analyze the existent conditions of the photonic bandgap (PBG), which is further demonstrated through experimental research. We utilize the method of transmission spectrum to measure the hollow-core microstructure fibers (HC-MSFs) in the visible and near infrared regions. The signal is obtained by detecting light from the end of the fiber. The experimental results indicate that there are several strong transmission bands in the near infrared region, but hardly any bandgaps in the visible region. Furthermore the attenuation in the visible wavelength is very considerable. The parameters of the HC-MSFs structure used in the measurement are the distance of nearest air holes pitch Λ (2.65μm), the diameter of air holes in the cladding d (2.10μm), and the central air core diameter (8.37μm). The spectrum positions of the bandgap in the spectrogram are 2297nm, 2406nm, and 2525nm, respectively. The repetition of the experimental results is fine.