A simple laboratory unit for calibration and testing seed drills was developed. It was consisted of iron frame, variable speed electric motor and two support rolls covered with rubber to control the ground wheel revaluations of the seed drill. The developed unit was checked by operating Colorado seed drill under different treatments, which included three simulated ground wheel speeds and three inflation pressures of the ground wheel. The outputs which affected by these treatments were application rate of wheat seeds and coefficient of variation. The results showed that, the developed unit had ability to move the ground wheel with stable revaluations. Average of the coefficient of variation of weight of the wheat seeds deposited from 21 tubes varied between 4.75 to 7.63%. The relative ease with which the unit is adjusted in the laboratory suits the technical know how of the factors affected on the imported or locally made seed drills could be studied.