Abstract: The traditional gas network performance analysis algorithm is based on the constant nodal flux as the constraint conditions to solve the nodal flux balance equations, which results in negative pressure in partial nodes. This paper presents an improved algorithm which is based on the nodal tri-state gas supply working mode of nodal pressure fluctuation. In the performance analysis, the relation between the nodal flux and the nodal pressure is considered. The dynamic response of the actual nodal flux which depends on the nodal pressure is also considered. The improved algorithm is verified to be reasonable and convergent by double gas supply medium pressure gas network. The result shows that the partial nodal pressure from the improved algorithm is larger than that of the traditional algorithm, and the iteration times is shorter than that of the traditional method. The computation case identifies that the improved algorithm is better than the traditional algorithm.