The present disclosure relates to an oven and a method for controlling thereof. When performing an air sous vide mode, a convection heater is controlled to turn-on and turn-off in a certain duration of the entire cooking operation based on a hysteresis algorithm. Specifically, a heat stage of the oven includes a first heat stage and a second heat stage, and in each cycle of the second heat stage, the oven may control the turn-on and turn-off of the convection heater based on the hysteresis algorithm from a first time point that arrives after the start time of each cycle. Accordingly, the cooking ingredient may be quickly heated in a sous vide method while temperature deviation of a cooking chamber is reduced.