The utility model discloses a mill weir case, include: box, water -permeable separator plate, wherein, the box both sides install the solid fixed ring of hoist and mount additional, and the level baris fixed to the fourth angle gauge model, and the front end is equipped with the triangle crest of weir, water -permeable separator plate installs in the box, the utility model discloses a stainless steel, it is anticorrosive, be difficult for getting rusty, the fixed measuring tape of the high department of flood peak installation (can adopt the stainless steel measuring tape of measurement authentication affirmation) is measured to box triangle crest of weir, reduces to measure and brings very big system error, can evenly lay 2 to 4 water -permeable separator plate draw -in grooves in weir incasement portion to setting up baffle quantity according to rivers water yield size fully, solving rivers not not simultaneously, the problem that hardly evenly steadily flows past is gone into to rivers behind the case of weir, and the practicality is stronger.