The invention discloses a cracker facilitating catalyst replacement. The cracker comprises a tubular shell and cracking pipes arranged in the axial direction of an inner cavity of the shell. A waste gas bypass pipe and a methyl alcohol preheating cavity are further formed in the shell in the axial direction. One end of each cracking pipe is provided with a methyl alcohol steam inlet, and the otherend of each cracking pipe is provided with a cracked gas outlet. The two cracking pipes are arranged, and the two cracked gas outlets are formed in the same direction. The invention further disclosesan alcohol hydrogen engine comprising the above cracker. According to the cracker facilitating catalyst replacement, the two cracked gas outlets are arranged in the same direction, two correspondingthreaded holes are arranged in the same direction, failure catalysts are conveniently directly poured out of the cracking pipes along the threaded holes, meanwhile, new catalysts are conveniently added in the cracking pipes through the threaded holes, the catalyst replacement time is shortened, and the catalyst replacement efficiency is improved.