The invention discloses a pipeline diameter measurement instrument multipath displacement pulse optimization device based on FPGA and a method, belonging to the pipeline detection technology field. The pipeline diameter measurement instrument multipath displacement pulse optimization device comprises a pipeline diameter measurement instrument main body, a plurality of odometers, a signal collection module, an optical coupling isolation unit and an FPGA central processing unit. The signal collection module comprises a plurality of convex lenses, a plurality of rotary encoders, and a plurality of light sensitive elements; each odometer wheel shaft is provided with a convex lens, a rotary encoder, and a light sensitive member; the convex lens, the rotary encoder, and the light sensitive element coaxially rotate along with the odometer wheel; the plurality of light sensitive elements are connected to the input terminal of the optical coupling isolation unit; the output terminal of the optical coupling isolation unit is connected to the input terminal of the FPGA central processing unit. The invention utilizes the FPGA parallel processing mechanism, improves the processing speed of the displacement pulse signal, effectively distinguishes the working state of a plurality of odometer wheels, solves the displacement accumulation error and improves the displacement measurement accuracy.