The invention discloses a rotary hoisting system which is used for lifting heavy objects. The rotary hoisting system comprises two lifting devices, and each of the lifting devices is provided with twolifting points. A first sling and a second sling are arranged on each of the lifting points. The invention further discloses a method for rotating the heavy objects when lifting the heavy objects byusing the rotary hoisting system. The rotary hoisting system is few in elements, simple in structure, light in weight, low in cost, and capable of rotating the heavy objects by 90 degrees.