The invention provides a steam boiler. The steam boiler comprises an upper boiler barrel, a lower boiler barrel, and an ascending pipe and a descending pipe which are connected between the upper boiler barrel and the lower boiler barrel, wherein a current stabilizer is arranged in the ascending pipe, and comprises a core and a shell, the core is arranged in the shell, the shell is fixedly connected with the inner wall of the ascending pipe, the core is an integrated structural member extending in the length direction of the shell, and a plurality of through holes are formed in the structural member. According to the steam boiler with a current stabilizer, adopting a novel structure, provided by the invention, when steam-liquid two-phase flow exists in the ascending pipe, the heat transfer is strengthened, besides, the vibration of the ascending pipe is weakened, and the noise level is reduced.