Optimization and experimental research on the cutting parameters of the cutter were carried out to solve the high re-cutting rate and loss rate under high-speed harvesting of alfalfa disc-type cutter. Kinematics theory was used to analyze the movement trajectory and cutting area of the cutter in the cutting process, and theoretical calculations to carry out an analysis of the factors affecting the re-cutting area of the cutter. A working parameters adjustable cutting test bench was designed and produced, and cutting experiments of alfalfa were conducted using this test bench combined with response surface methodology. The optimized factors combination was solved by quadratic fitting function, and the value of cutterhead diameter, blade twist angle, and cutting inclination angle was 407.04 mm, 4.21°, and 4.51°, respectively. The verification test showed that the average re-cutting rate and loss rate were 1.48% and 3.13%, less than national standard requirements for alfalfa harvesting quality (re-cutting rate <1.5%; loss rate <4%), low-loss cutting of alfalfa was achieved, and the harvesting quality of the disc-type cutter was improved.