Strawchopping device with chopping and fixed knife supported slide cutting was designed, which was suitable for horizontal maize straw crushing machine. The supported slide cutting force formed by equal slidingcutting angle fixed knife and the highspeed spinning chopping knife along with the roller of device was used to crush straw. The cutting edge curve of fixed knife was logarithmic spiral curve equation. The chopping knife was made up with parallelstraightening blade and modified Lmachetes. Combined with the characteristics of corn straw, the parameters of key components were confirmed, and then the ANSYS-Workbench software was used to check the static strength finite element analysis of fixed knife, the mode of crushing roller was analyzed and a series of stress figures of the fixed knife and the first six frequencies and corresponding mode shapes of crushing roller were obtained. The result of finite element analysis showed that the maximum stress of fixed knife was occurred on its posterosuperior, the value was 13841MPa, and the materials met the requirement. The work frequency of crushing roller (23.3~30Hz) was far below its first natural frequency (102.62Hz), thus the resonance phenomenon would not occur. The field experiments showed that the straw crushing average qualified rate was 91.5%, when the strawchopping device with chopping and fixed knife was at 1600r/min of the crushing roller, the power consumption can be reduced by 17.4% compared with the device without fixed knife (1800r/min).