Abstract: Under four different working conditions(the smallest air valve α_py=1.6, the smaller air valve α_py=2.2, the larger air valve α_py=3.2 and the largest air valve α_py=4.4), the double fire grate boiler designed by the author was tested. The corresponding result is that the temperature distribution appears similar law in height, depth and width direction. Secure, stable and economical operation of the boiler can be realized on the better work state(between state 2 and state 3). It could be an important type of straw briquette boiler. It lays foundation for optimization design of burning equipment and running adjustment.