A movable burner of a gas cooktop includes a rotating shaft, a linear motion mechanism configured to perform a linear motion, a burner head, and a limit unit configured to limit a stroke range of the linear motion mechanism. The burner head includes a plurality of brackets having a plurality of gas outlets for gas to flow out and form a flame. Each bracket is separately hinged to the rotating shaft and separately connected to the linear motion mechanism such as to execute a rotation about the rotating shaft between at least two working positions, when driven by the linear motion mechanism, with the burner head having a flat upper surface in one of the two working positions, and with the burner head having a concave configuration in the other one of the two working positions.