The invention discloses a method for distributing balancing and locking cylinders for a large multi-cross roll straightening machine, comprising the following steps: 1. the locking cylinders and the balancing cylinders are respectively arranged in the four symmetrical positions of a sliding seat to form three-dimensional arrangement; 2. the locking cylinders are arranged in the sliding seat; 3. the balancing cylinders are arranged on a lower steel plate between the sliding seat and an upper rack (3) to be used for balancing the weight of an upper roll device and a turnplate and removing the gap between elevating screws to ensure the adjusted roll gap to be more accurate; 4. a piston is connected with a permanent seat on the sliding seat (5) and a protecting cylinder (2) is arranged on the upper rack; and 5. the balancing cylinders (1) and the locking cylinders (4) are designed on the periphery of the sliding seat and are arranged symmetrically. In the method, three-dimensional and hierarchical design is adopted, the designed cylinders have larger diameters and the overall size of the equipment is smaller, thus the large tube and bar straightening machines have reasonable structures, and the designed cylinders have beautiful appearances, are more convenient and reliable to use and are suitable for the large diameter multi-cross roll tube and bar straightening machines.