The invention discloses a process for filtering carbonylation liquid produced from MMT (Methyl-cyclopentadienyl-Manganese-Tricarbonyl). The filtering equipment comprises a carbonylation kettle, a liquid input pump, a horizontal screw centrifuge, a liquid return pump and a filtrate storage tank, wherein the liquid outlet at the bottom of the carbonylation kettle is connected with the liquid input pump through a pipeline; the liquid input pump is connected with the inlet of the horizontal screw centrifuge through a pipeline; a slag-drip opening of the horizontal screw centrifuge leads to a slag discharging pool; the filtrate outlet of the horizontal screw centrifuge is connected with two branch pipes; the first branch pipe leads to the liquid return outlet of the carbonylation kettle through the liquid return pump; the other branch pipe leads to the filtrate storage tank. According to the filtering equipment disclosed by the invention, the completed fresh carbonylation filtrate is recycled, the addition amount is 3-5% of the total volume of the reaction, the carbonylation filtrate is stable in property and does not participate in the reaction, while tiny salt particles in the carbonylation filtrate can serve as a high-efficiency nucleating agent. Therefore, the cost is not increased, the yield of a single kettle is not influenced, and the slag content in the filtrate can be reduced from 10% to 2%.