The invention discloses a various-fuel and environment-friendly boiler. The various-fuel and environment-friendly boiler comprises a first combustion chamber, a second combustion chamber, a first heat exchanging chamber and a second heat exchanging chamber which are sequentially communicated, wherein the first combustion chamber, the second combustion chamber, the first heat exchanging chamber and the second heat exchanging chamber form a shape like the Chinese character 'tian', and every two adjacent chambers of the four chambers is separated by a partition; the lower ends of the partition between the first combustion chamber and the second combustion chamber and the partition between the first heat exchanging chamber and the second heat exchanging chamber are provided with lower openings for communication; the upper end of the partition between the second combustion chamber and the first heat exchanging chamber is provided with an upper opening for communication; the partition between the first combustion chamber and a fourth heat exchanging chamber does not have an opening. The various-fuel and environment-friendly boiler has the advantages that the boiler is provided with the plurality of combustion chambers and heat exchanging chambers, the boiler is reasonable in structural design, various-fuel combustion is achieved, multi-return-stroke moving around is achieved, heat utilization rate is increased, and the boiler is clean and energy saving.