The invention discloses a crane main beam. The crane main beam comprises a first web, a second web, reinforced frames, a top plate and a bottom plate. The top plate is connected with the top of the first web, and the bottom plate is connected with the bottom of the second web. The reinforced frames are arranged in the main beam at intervals and are fixedly connected with the first web, the second web, the top plate and the bottom plate respectively. The first web and the second web are each provided with a camber. The first web and the second web are both formed in a sequence welding manner. Staggering distances are set between segmented weld joints of the first web and between segmented weld joints of the second web. Due to the fact that the first web and the second web of the main beam are formed in the sequence welding manner and a certain staggering distance is kept between every two adjacent segmented weld joints of the two webs, stress of the main beam is dispersed because of arrangement of the weld joints; due to a new machining technology, the rigidity of the main beam is enhanced, and flexibility caused when a long-span main beam generates bending moment because of dead weight is effectively prevented.