An efficient combustion boiler comprises a shell and a combustion chamber arranged in the shell. A water storage chamber is arranged between the shell and the combustion chamber. A fire grate is arranged on the lower portion of the combustion chamber and comprises a first circular supporting pipe attached to the inner wall of the combustion chamber and multiple rib pipes longitudinally arranged on the first circular supporting pipe side by side. The first circular supporting pipe and the rib pipes are provided with multiple upward-air-exhausting holes exhausting air upwards. A feeding opening is formed in the side end of the upper portion of the combustion chamber. A sealing cavity penetrating the feeding opening is obliquely arranged in the chamber wall of the combustion chamber. A transmission device and a sliding door are arranged in the sealing cavity. A feeding channel is arranged on the portion, on the outer side of the sliding door, of the combustion chamber and sleeved with an outer feeding cover. A spiral plate spirally arranged along the feeding channel is arranged between the feeding channel and the outer feeding cover. By means of the efficient combustion boiler, heat leakage can be prevented effectively, dust emission is reduced, combustion efficiency is improved, combustion is sufficient and even, and the utilization rate of fuel heat is increased.