SZL series vertical dual drums chain grate water pipe steam and hot water boiler, adopts quick fitting and assembly structure. The 4-6t/h boiler is of quick fitting pipe structure, exit shop after completely assembled, the boiler of 6-35t/h is composed of 2 main components. The upper assembled components is the body heat accepting part, and the lower assembled component is of combustion equipment. The former part of the boiler body is arranged an water cooling wall, the upper part of it is connected to boiler cylinder, and its lower part is connected to collective chest, so as to form a combustion room and absorb the radiated heat from the furnace. Its rear part is arranged with dense convection pipes between upper and lower boiler cylinders. The high temperature smog after combustion shall stand for twice returning flushing transversely to the heat accepting surfaces, and shall be introduced to coal saver singly arranged, and flow into duster and exhausted from chimney in the end.