The invention relates to a ground mounted derrick, which comprises a derrick main body consisting of standard sections. The ground mounted derrick is characterized in that the bottom of the derrick main body is provided with a lifting frame; a jacking oil cylinder is arranged at each of two sides of the lifting frame; an operation platform is arranged beside the movable end of each jacking oil cylinder; the middle part of the derrick main body is provided with a pump station and a winding section; the upper end of the derrick main body is provided with a support seat; a pivoting supporter is arranged on the support seat; a rocker arm seat is arranged on the pivoting supporter; a rocker arm is arranged at each of two sides of the rocker arm seat; the middle part of the rocker arm seat is longitudinally provided with a mast; the top end of the mast is provided with variable-amplitude steel wire ropes; each variable-amplitude steel wire rope is wound on the movable end of the corresponding rocker arm; and a hoisting steel wire rope is also wound on the movable end of each rocker arm. The ground mounted derrick has the advantages that the stable hoisting can be realized; the occupied ground in the field and the number of personnel for tower assembling construction are reduced; the energy is saved; the environment is protected; and safety and reliability are realized.