The prior arts generate bubbles with fixed characteristics of the gas in the bubbles. The invention proposes an apparatus of generating bubbles and a method thereof. The apparatus comprising: a first unit (10) configured to determine at least one characteristic of a gas in the bubbles; a second unit (12) configured to generate the bubbles, comprising: an electrolyzer (120) configured to electrolyze an electrolyte to generate the gas in the electrolyte, thereby generating bubbles; and a controller (14), configured to control the second unit to generate the bubbles according to the at least one characteristic of the gas. In embodiments of the invention, the generation is controllable with respect to the gas in the bubble based on the practical requirement of the gas, and is more flexible and with wide applicability.