Surface irrigation is the most common method for crop irrigation in Iran. This method needs uniform surface slope regard to texture of soil, plant and natural slop of land. Land leveling can increase irrigation efficiency and yield crops. During land leveling, topsoil is scrapped away from area of relatively high elevation and deposited in relatively low elevation with minimum traorting. By improve of technology, land leveling machines equipped with laser system. This system is included laser transmitted, laser receiver and control box. In automatic mode of laser system, blade state is set by control box respect to desired plane, which provided via laser transmitter. During leveling, if the cutting depth of any points is so high as power needed is higher than tractor drawbar power, it will lead to undesired slippage and extra load on the engine of tractor. The tractor will be shut down if this state continued. To prevent the overload on machine and tractor, the driver must be change auto mode of laser system to manual, immediately and decrease depth of cutting simultaneity. This needs driver skill and high response. In order to preventing the overload during leveling, an extra blade depth controller was designed and fabricated in this project. The designed system consisted of a closed loop, which gets the real tractor engine speed via dynamo and compared the critical and desired speeds of engine, were defined by user via manual keyboard. These data were recorded in main microcontroller memory (programming in one hundred thirty line codes with AVR-Codevision software), and display it on LCD online. At critical engine speed caused by overloading, the system governs blade depth until disrupt. The depth controller system send adequate pulse to solenoid valve of adjuster blade depth cylinder to decreasing depth until approach the desired speed of engine. After eliminating the overload, the system switching blade commands to laser control box. The fabricated system was set on land leveling laser machine and evaluated in farm. The fuel consumption and field performance of machine were determined with and without using the fabricated system. The test was carried according to the T-test with five replication. Each experimental field has nearly the same size in approximately one hectare and rectangular dimensions and similar cutting volume. Result showed significantly difference at the 5% level between using and not using the fabricated system ( p 0.05 ). Using the fabricated system caused reduce 18.36 percent in fuel consumption and 19.74 percent in field performance. Key words Laser land leveler, closed loop control system, overload.