Abstract: According to hard X-ray temporal, spectral and spatial characteristics,solar f-lares are identified as type A, B and C. In this paper, the spatial structure and he-light distribution of hard X-rays in flare loop with non-uniform cross section are an-alysed. The formation and characteristics of hard X-ray sources for the three type flares are discussed. It is shown the structure and distribution of hard X-ray sourc-es are closely related with the parameters of magnetic structure of background plasma and spectrum of non-thermal electrons.