The utility model discloses a bidirectional pressure free briquette boiler. A carrier frame is arranged on the fire bar to lay the briquette, and a pushing briquette device is arranged at the front end of the boiler body; an entering briquette door is arranged at the front side wall, and a cleanout door is arranged at the back end or the back side wall; the corresponding area of each air door under the fire bar is spaced by a partition board, and a fire pipe is fixed on the both ends of the laying fire board which is high at the front part and is low at the back part; a chimney whose inner part is provided with a draught controller is arranged on the smoke chamber, and a side-water board which is communicated with a filling water chamber is arranged at the both sides of the hearth; a backwater inlet is arranged at the lower part of the back boiler body, while a hot water outlet is arranged on the upper boiler body; the boiler bodies can combine from top to bottom or from right to left, to become a briquette boiler with double and multiple burning chambers. The utility model has the advantages of high heat efficiency, no pollutant emission, noiselessness and low running cost.