The multipliers A and B are in relation to pressure p and temperature T respectively. By coupling Eqs. (10), (11), (14) and (15), the variables U, T, p and B can be solved to obtain a solution of problems in the convective heat transfer process. The results about changes of temperature field and flow structure in circular tubes can be gotten through solving equations above by the way of numerical calculation, and heat transfer and flow resistance can be researched.