The invention relates to an efficient transmission device of a dry-mixed mortar stirring machine. A stirring motor is arranged above a vertical axis planetary reducer and connected with a driving pulley. The driving pulley transmits power to a driven pulley through a transmission belt. The driven pulley is connected with the vertical axis planetary reducer. The vertical axis planetary reducer is fixed to a stirring barrel body through a reducer seat. The output end of the vertical axis planetary reducer is matched with a spline sleeve, and the spline sleeve is matched with an output shaft to bring the output power to a stirring arm for rotation. The efficient transmission device of the dry-mixed mortar stirring machine has the advantages of being reasonable in mechanism design, flexible in output, convenient to assemble and maintain, low in cost, high in stirring efficiency and the like, and is particularly suitable for being applied to the dry-mixed mortar stirring machine in the construction machine industry, simple in structure and high in practicability.