The invention provides a steam valve and a cooking appliance, wherein the steam valve comprises a valve body and a bubble breaking piece; a steam cavity is formed in the valve body; a steam inlet and a steam outlet are formed in the steam cavity; the bubble breaking piece is arranged in the steam cavity; a bubble breaking cavity is formed in the bubble breaking piece; a steam inlet hole, which communicates with the steam inlet, and a steam outlet hole, which communicates with the steam outlet, are formed in the bubble breaking cavity; and the longitudinal sectional area of the bubble breaking cavity is gradually diminished from middle to two ends. According to the steam valve provided by the invention, the inner cavity (the bubble breaking cavity) of the bubble breaking piece is represented in the form of a submarine; when rice grains, porridge, soup and the like enter the steam valve along with steam as steam pressure in the cooking appliance is relatively high, the submarine-like inner cavity can take a squeezing effect on the steam, so that the rice grains, the porridge, the soup and the like, which are entrained in the steam, can be gradually separated from the steam in the bubble breaking cavity and then can drop back into the bubble breaking cavity; therefore, a good bubble breaking effect is achieved, the circumstance that the rice grains, the porridge, the soup and the like spill over of the cooking appliance is effectively prevented and the convenience of a user in cleaning is enhanced.