Abstract: Basic characteristics of oscillating flow are analyzed from thermoacoustic angles.Transverse velocity distribution caused by viscosity and transverse temperature distribution caused by heat wave in a tube are discussed.Heat conduction within flow channel can be classified into three areas,isothermal area,delayed area and adiabatic area.The micro-thermodynamic-cycle areas which thermoacoustic parts work are defined based on their different functions on a thermoacoustic system.This result is helpful to design thermoacoustic system.