A valve includes a valve body and a valve core rotatably disposed in the valve body; the valve core is provided with a gas inlet channel in communication with a gas source; and a sidewall of the valve core is provided with an inner ring fire gas outlet and an outer ring fire gas outlet that penetrate the sidewall. The valve body is provided with an inner ring main gas outlet channel and an inner ring fine-tuning channel corresponding to the inner ring fire gas outlet, and the valve body is provided with an outer ring main gas outlet channel and an outer ring fine-tuning channel corresponding to the outer ring fire gas outlet. During firepower adjustment, when the outer ring main gas outlet channel is staggered from the outer ring fire gas outlet, the outer ring fine-tuning channel will continue supplying gas within a certain angle rotation range, and after the inner ring main gas outlet channel is staggered from the inner ring fire gas outlet, the inner ring fine-tuning channel will continue supplying gas, so that the entire gas flow control curve becomes smoother, thereby facilitating users in precisely controlling firepower of the gas cooker.