Using self-made semi-solid mechanical stirring process system, the solidification behavior of Pb-15wt% Sn alloy semi-solid slurry with solid fraction beyond 0.6 was investigated under stirring condition. A detailed microstructural analysis of the solid phase was carried out. The results show that the solid-liquid separation is obvious in the samples with the solid fraction beyond 0.6 and the solid phase is dispersed quasi-globular particles. Based on these results, a kind of single-crystal powders coated with Pb-Sn eutectic was made by continuous stirring and cooling under the semi-solid state and a new method for preparing metal powder is developed. The analysis and discussion indicate that this approach can reduce the content of oxide and impurity in the powder.