According to the characteristics of hollow billets, a hot-top electromagnetic continuous casting process is proposed, based on a combination of the hot-top technique and a cold crucible. Sn-4.5%Pb (wt%) was used as the experimental material to study the effect of hot-top and cold crucible outer mould on the distribution of electromagnetic field. The effect of the electromagnetic field on the quality of hollow billets was analyzed. The results indicated that use of the hot-top with screen and cold crucible outer mould, while imposing an electro- magnetic field of 12 kW with the frequency of 2 500, can improve the distribution of electromagnetic field in the mold. In this ways high quality hollow billets can be obtained, whose solidification macrostructure consists of equiaxed grains of high ratio and a smoother surface.