Stationary threshing and winnowing machine model El-Haddad-WZ-1 for small holding was designed by El-Haddad, 2000 in Agricultural Engineering Dept., Faculty of Agric., Kafr El-Sheikh University. It was tested in Rice Mechanization Center for threshing and winnowing of rice crop. It was used to chopandshred rice straw crop tomaximize the performance of this machine and increasing yearly working hours, Results of the original machine showed that, it can not cut rice straw into small pieces without accumulation problems occurred in the threshing chamber especially with feeding of complete stalks sample at high moisture content. This problem causes wasting time, less productivity, and increase cost. Consequently, it is necessary to develop this machine for the young farmer to cut some crop residues as rice straw, corn stalks and cotton stalks. The machine after modification was operated at four cylinder speeds, 4.55, 6.07, 7. 59 and 9.11 m/s (300, 400, 500 and 600 r.p.m.), four feed rates of 2, 4, 6 and 8 kg/min, and three levels of moisture contents of 22.3, 25.5 and 30.3% (wb) for rice straw, respectively. Machine performance, chopping machine capacity (kg/min), cutting length of straw, power consumption (kW), useful power (kW), unit energy (kW.h/Mg) and criterion function cost, were studied in this research. Results of the development machine showed that the percentage of small cutting lengths, were increased by increasing cylinder speed and feed rates and decreased by increasing the moisture contents. The maximum of the percentage of small cutting lengths were (21% > 0.5 cm, 50 % from 0.5 to 1 cm, 12% from 1 to 2 cm and 17% from 2 to 3 cm), at cylinder speed 9.11 m/s (600 r.p.m.) and moisture content of 22.3% in straw and feed rate 8 kg/min.