Abstract: There has been a continuous growth for applying large diameter horizontal thin-walled circular cylindrical shell (HTCCS) for air and flue gas ducts, raw coal or pulverized coal piping. HTCCS under nonaxisymmetric loading is usually designed according to the membrane theory or global beam theory, which is inadequate to capture the bending and shear stresses in the shell located near the load edges. In this paper, the total internal forces in a thin HTCCS under ashes, snow, wind, gravity or seismic loads are determined from the combined membrane and moment theories. The exact solutions obtained complies with the results of finite element analysis. These study results can be extended to the design of HTCCS subjected to similar non-axisymmetric loading.