The invention discloses a process for preparing methanoic acid by methyl formate hydrolysis. The process comprises the following steps: methyl formate containing methanol is firstly sent to a methyl formate tower for separation, the methanol is extracted at the tower bottom, and the methyl formate extracted at the tower top is sent to a catalytic rectification tower; the methyl formate hydrolyzeswith water in a reaction section of the catalytic rectification tower, the methyl formate extracted at the tower top and the methanol are returned to the methyl formate tower for separation, and methanoic acid aqueous solution extracted at the tower bottom is sent to an extraction rectification tower; an extractant is added from the top of the extraction rectification tower, the water is extracted at the tower top, the extractant, the methanoic acid and a small quantity of the water which are extracted at the tower bottom are sent to a vacuum rectification tower; and the extractant extracted at the tower bottoms circulates to the extraction rectification tower after decompression and separation, and the methanoic acid product with 85%-99% mass concentration is extracted at the tower top. The process can cause the one-way hydrolysis conversion rate of the methyl formate to reach 70%-99%, shortens process flow and saves equipment investment and energy consumption.