The present disclosure provides a reactor and a method for the production of high purity silicon granules. The reactor includes a reactor chamber; and the reaction chamber is equipped with a solid feeding port, auxiliary gas inlet, raw material gas inlet, and exhaust gas export. The reaction chamber is also equipped with an internal gas distributor; a preheating unit; and an external exhaust gas processing unit connected between the preheating unit and a gas inlet. The reaction chamber is further equipped with a surface finishing unit, a heating unit, and a dynamics-generating unit. The reaction occurs through decomposition of silicon-containing gas in a densely stacked, high purity granular silicon layer reaction bed in relative motion, and uses the exhaust gas for heating. The present invention achieves a large-scale, efficient, energy-saving, continuous, low-cost production of high purity silicon granules.