The invention relates to a water-based polyurethane continuous synthesis method based on impact mixing and continuous emulsification. The method comprises the following steps: mixing polymer dibasic alcohol, triethylamine, DMPA (dimethylolpropionic acid) and 1,4-butanediol to obtain a raw material A, using diisocyanate as a raw material B, and respectively storing the raw material A and raw material B in two raw material tanks; mixing deionized water, a chain extender and an emulsifier to obtain a raw material C, and storing the raw material C in a raw material tank; adding the raw material A and raw material B into a first polyurethane casting machine, mixing to obtain a mixed solution, sending the mixed solution into a first reaction pipeline, and carrying out reaction at 85-90 DEG C for 15-20 minutes; and mixing the reaction product of the raw material A and raw material B with the raw material C to obtain a mixed solution, sending the mixed solution into a second reaction pipeline, and carrying out reaction at 45-50 DEG C for 10-15 minutes, thereby obtaining the water-based polyurethane. The method can continuously and quickly produce the water-based polyurethane, and has the advantages of stable production technique, stable product quality and high product performance.