The invention relates to a mixing device, in particular to a slurry mixing device for a construction site. The invention aims at solving the technical problem of providing a slurry mixing device for aconstruction site which can sufficiently and uniformly stir the slurry in the mechanical stirring process and can prevent people from breathing a great amount of pungent smells. The slurry mixing device for the construction site comprises a bottom plate and a speed reduction motor; and the upper left side of the bottom plate is provided with the speed reduction motor and a supporting rod, the speed reduction motor is disposed on the left of the supporting rod, the upper end of the supporting rod is provided with a guide sleeve, and a movable frame is arranged in the guide sleeve in a slidingmanner. By adopting the slurry mixing device, a mechanized stirring process can be achieved, sufficiency and uniformity in stirring can be realized, and people can be prevented from inhaling a great amount of pungent smells; and the mixing box continuously moves left and right, so that a rotating stirring blade can sufficiently stir the powdery raw material and liquid in the mixing box, when the powdery raw material and liquid are mixed, the peculiar smell and pungent smell can be scattered, and the odor is difficult to gather.