To clarify the stabilization, destabilization and secondary flow effects of the Coriolis force on the turbulence structure in rotating channels with high and low aspect ratios, experimental investigations were undertaken by using a rotating wind tunnel about 2 meters in diameter. A hot-wire anemometer and more than 6 hot-wire probes with fine resistance wire, each inclined at a known angle to the main flow, were used for the measurements of time-mean velocities and 6 components of Reynolds normal and shear stresses. An optical transmission system of electrical signals from a rotating apparatus to the stationary system was used to immunize the electrical noise. The hot-wire probe was traversed with sufficient accuracy. Phenomena of the stratification, Taylor-Görtler type vortices in the destabilized nominal two-dimensional turbulent boundary layer, relaminarization from turbulent to laminar boundary layer in the high aspect ratio channel and a pair of longitudinal flat vortices in the low aspect ratio channel were observed, and discussed in detail by using the low of conservation of angular momentum, the vorticity transport equation and the Reynolds stress transport equations in a rotating frame.