在前人工作的基础上，从辐射传热的基本原理出发，给出了描述灰介质辐射传热的一组控制微分方程组。该方程组克服了目前热流法中空间、方向耦合差的缺陷，并反映了辐射传热的三维本质特性，同时也引进了辐射热流方向耦合系数矩阵、辐射热流通量、辐射场强等概念。该方程组较容易与其它传输方程耦合在一起，解决生产实际问题 Based on the previous work, a set of governing differential equations describing the radiative heat transfer of the gray medium is given based on the basic principle of radiative heat transfer. The equation overcomes the defects of the current heat flow method in space and direction coupling, and reflects the three-dimensional nature of radiative heat transfer. At the same time, the concepts of directional coupling coefficient matrix, radiant heat flux and radiation field are also introduced. The equations are easier to couple with other transport equations to solve practical problems in production