Experimental investigations on the flow patterns of air-water two-phase flow in a vertical circular channel and a vertical equilateral triangular channel were carried out. Instinct understandings of two-phase flow regimes affected by the shapes of the cross-sections of the channels were gotten by flow visualization with the aid of a digital video camera. The following flow patterns at different air and water superficial velocities were recognized for both channels: bubble flow, slug flow, churn flow, and annular flow. For the air-water flow at high Reynolds numbers in the equilateral triangular channel, two new flow patterns were found besides the above-mentioned flow patterns: one is called "Secondary Flow Creep Flow", and the other is named as "Capillary Creep Flow". Secondary flow creep flow takes place in the zone of SG V=35-95m/s, SL V=0.0004-0.016m/s. Three liquid streams driven by secondary flow exist in the middle of the sidewall of triangular channels. Capillary creep flow is found in the zone of SG V=15-30m/s, SL V=0.0004-0.016m/s. In this case, secondary flow is not strong enough to drive liquid to the center of sidewall, instead, liquid gathers in the corner due to the capillary force. The observation of creep flows in the equilateral triangular channel proves that secondary flow will affect two-phase flow patterns in noncircular channels at high Reynolds number.