The utility model discloses a free -fall concrete mixer device, including bottom plate and agitator, the top of bottom plate one side fixedly connected with machine case, the inner wall bottom of quick -witted case be fixedly connected with water pump and second motor in proper order from left to right, the first motor case of top fixedly connected with of quick -witted case, and one side fixedlyconnected with feeder hopper of quick -witted case is kept away from to the agitator, and the bottom of feeder hopper is fixed and is provided with weighing plate, and one side from the top down of feeder hopper has set gradually display screen and water yield detection device, the utility model relates to a mixer technical field. Reach the more abundant purpose of messenger concrete mixing, increaseed the dynamics to concrete mixing to through weighing plate and water yield detection device, the science is accurate more to make the interpolation of each batching of concrete and water, and thebottom fixedly connected with wheel of bottom plate makes the mixer more convenient in the during operation removal.