The purpose of this paper is to explore the fuel and ash characteristics of maize straw (MS) char briquettes. The biochar briquettes were made from different pyrolysis temperatures and additives. The pyrolysis and combustion processes were performed in a fixed-bed furnace system. Ash fusion temperatures were tested in an ash fusion point analyzer. Pyrolysis product properties under different pretreatments were analyzed by a combination of X-ray powder diffractometry, scanning electron microscopy with energy-dispersive spectrometry, Fourier transform infrared spectroscopy, and X-ray fluorescence. The high fusion tendency of MS char was observed thorough ash fusion indexes. The softening temperature decreased with a deduced base to acid and an elevated pyrolysis temperature. Aromatization became obvious in a high-temperature pyrolysis product. KH2PO4 and Ca(PO3)(2) were detected in MS ammonium dihydrogen phosphate and MS calcium phosphate monobasic, accompanied by the decreasing intensity of KCl. Phosphorus grains attached on fibers, reacted, and transformed the K element into K-Ca-P compounds. As a result, ash fusion temperatures and fusion phenomena were greatly improved by adding NH4H2PO4 and Ca(H2PO4)(2) in the pretreatment.