The Rotary Drum Grass Mowing machines are connected to tractor via three-point hanging system and get its drive from the PTO at 540 rpm and transmit to the drums through belt pulley. It is a grass mowing machine with free oscillated blades which are on the two drums rotating in reverse to each other with this system to cut green feed plants (clover, grass plants, barley, oat, etc.) being opened by the effect of centrifugal force and leave on the surface of the field in barrel state. The Drum Grass Mowers which are manufactured ideal for all sorts of the farms are designed to use with the tractors having lower and medium horse powers. Leaving the product on the ground in a better barrel state by means of the lower drums be able to rotate idle without damaging especially the wet and bent products using even a very low powered tractor is one of its features. The Grass Mowing machine is protected against the damages which may incur due to some roughness on the field. Thanks to the shock absorbing spring system available in the machine, the machine recovers the shapes according to the field and prevents the damages which the machine may encounter. Thanks to the hydraulic system existed in the machine, mowing at any angle can be achieved.