A method and device for detecting pyrethroid pesticide residues in crops. Reaction membrane is arranged on a bottom plate and provided with a check-up line and a quality control line; a first mounting block and a second mounting block are arranged on the bottom plate; a first slide is arranged in the first mounting block, a second slide is arranged in the second mounting block; a sample pad and a bonding pad are arranged in the first slide; a water absorption pad is arranged in the second slide; a liquid inlet provided with a pipe is formed in the first mounting block, a pressing hole provided with a press block is formed in the second mounting block; protrusions are respectively formed on the pipe and the press block; sliding grooves are formed in the liquid inlet and the pressing hole; and first springs are arranged between the protrusions and the sliding grooves.