Abstract: PIV（Particle Image Velocimetry） was used to study the velocity profile in the flow field and the wake characteristics of single air bubble rising in a vertical narrow rectangular channel. Effects of inlet average fluid velocity and bubble diameter on bubble rising velocity, wake structure and velocity profile were analyzed. Rising of the inlet average fluid velocity can reduce the wake disturbance induced by the rising bubble and simplify the wake structure. At a distance less than 1.0 W（W is the channel width, mm） behind the bubble tail, disturbance is greater compared to zone beyond 1.0 W from the bubble tail.