The different combinations of segment ring width, segment partition and bolt number are studied for Tianjin municipal drainage shield tunnel, and comprehensive comparison is made in terms of wedge quantity calculation, rational assembly point determination, theoretical layout fitting, construction capacity analysis, construction efficiency, waterproof performance, segment overall stiffness, etc., so as to finally determine the rational segment ring width, segment partition and bolt number. Some main conclusions are drawn as follows: (1) According to the characteristics of this project, it is relatively rational to choose ring width of 1.2 m, segment partition of 5 blocks and bolt number of 13 groups. (2) When designing the main structural parameters of the segment, necessary theoretical calculation and analysis should be carried out according to the engineering characteristics and actual functional requirements to determine relevant segment parameters, and as well, current investigation, engineering analogy and relevant engineering experience should be considered. (3) The segment ring width should be determined comprehensively according to the tunnel curve radius and the construction risk of tunnel attitude control. (4) Relevant theoretical studies should be carried out on the parameter design of smalldiameter shield segment.