Abstract: China is one of the most important cotton?producing areas in the world.It is well known that cotton stalk is a kind of renewable biomass energy resource and can be widely used.Therefore, it is very important to research the harvesting techniques and equipment of cotton stalk, and design the cutting blade of cotton stalk.The conception of cutting effective rate was put forward on the basis of analyzing the cutting pattern of the reciprocating cutter, and it was used to describe the cutting characteristics of reciprocating cutter, because the cutting pattern of the reciprocating cutter could describe the cutting quality and height of the stubble of cotton stalk.In order to explore the effect of the knife section structural parameters(the width, height, and leading end width of the knife section) as well as the operating parameters(the average cutting velocity was 0.9 m/s, and the ratio of cutting velocity to feeding velocity was 1.25) on cutting effective rate of cotton stalk reciprocating cutter, and optimize the structural parameters of the knife section, the simulation test was performed with the ADAMS software.The simulation testing scheme designed with the box?behnken design(BBD) method was a three?factor three?level testing scheme, and the testing factors were the width of the knife section, the height of the knife section cutting edge, and the width of the leading end.The response surface analysis method was used to analyze the simulation testing data and optimize the knife section structural parameters of the cotton stalk reciprocating cutter.In order to observe and analyze the cutting process and morphological structure of the stubble as well as optimize the profile of the knife section, the cutting test was performed with a cutting test bench of cotton stalk by the high?speed photography technology.The samples were the ripe cotton stalks with the diameter of 11.7-13.2 mm, and the moisture content of 31%-37%, which were collected from a cotton field located at Shanghe County, Shandong Province.The results obtained from the response surface test showed that the effects of the width of the knife section, the height of the knife section cutting edge, and the width of the leading end on the objective value(the cutting effective rate) were significantly different(P<0.01), and the effects of the interactions between the width of the knife section and the height of the knife section cutting edge, between the width of the knife section and the width of the leading end, and between the height of the knife section cutting edge and the width of the leading end on the objective value were also significantly different(P<0.01).By analyzing the sequence images of cutting process of cotton stalk from the cutting test by the high?speed photography technology for cotton stalk, it was known that the effects of the different profile of the leading ends on the cutting quality of cotton stalk and the height of the stubble of cotton stalk were significantly different.It was concluded that the optimal combination of the knife section structural parameters of cotton stalk reciprocating cutter was that the width of knife section was 90 mm, the height of knife section cutting edge was 52 mm, the width of leading end was 15 mm, and the profile of leading end was arc?shaped.On the basis of the results of the verifying tests, it was found that the cutting effect of cotton stalk for cotton stalk reciprocating cutter with the new knife section was good, the height of cotton stalk cutting stubbles of the optimized knife section was 5.9 mm shorter than the standard knife section′s, the average value of cutting power per unit area of cotton stalk for the optimized knife section was 6.1% less than the standard knife section′s, and the smoothness of cutting stubble section of cotton stalk for the optimized knife section was 12% more than the standard knife section′s.The results of this research can provide technical support not only for developing a new cotton stalk cutter, but also for designing the equipment for harvesting hard stalk with a large planting area.