This research aims to develop and fabricate an innovative and simple prototype of a grading machine for citrus fruits. This research was conducted in the workshop at the college of Agri. Eng. Al-Azhar Univ., Assiut. Design feature includes three major characteristics are a simple design and ease of use, its parts are locally available materials and ease of construction in addition to possibility sizing most of spherical fruits by changing some adjustments. The machine was adjusted to the grading of Valencia orange fruits into five categories. The results revealed that the suggested design achieved high sizing efficiency by using the machine at an angle of inclination of the tilted flat (A_f) that corresponds to the coefficient of static friction of fruit types graded. Also, the roller of the grading system must rotate against the fall of the fruit in order not to get stuck between the roller and the tilted flat. But, it was clear that no effect for speeds of the revolving roller on the machine performance. Percentages of the machine efficiency were 78.2, 94, and 77.8 % at values of the angle ( ) 16^o, 20^o and 24^o respectively using the speed of the revolving roller (  = 10 rpm). Also, the results indicated that the machine throughput capacity did not change significantly by increasing the speed of the revolving roller at any given angle. The maximum values the machine throughput capacity were 105, 136.8, and 152 kg/h. at values of the angle ( ) 16^o, 20^o and 24^o respectively using the speed of the revolving roller (  = 10 rpm).