The invention relates to an isolation barrel for a flotation pulp liquid level measuring device. The isolation barrel comprises a barrel body and a connecting pipe, wherein the barrel body is used for accommodating a measuring float; the lower end of the barrel body is connected with the connecting pipe; the connecting pipe forms an inclination angle with the horizontal direction; the barrel body is communicated with pulp liquid through the connecting pipe; and the end face of the bottom of the connecting pipe is a vertical plane. The measuring float is arranged in the barrel body connected with the connecting pipe, so that inflated pulp is isolated from the measuring float, and the influence of pulp foam on measurement is eliminated; and the connecting pipe forms a certain inclination angle with the horizontal direction, so that the pulp liquid forms a certain angle with the vertical direction and enters the barrel body, and the impact effect of the pulp in a tank on the measuring float when the pulp vertically and horizontally fluctuates is avoided under the condition of ensuring that the barrel body is communicated with the pulp; and therefore, the pulp liquid level is stably and accurately measured.