Firstly, a pretypesetting calculation method for staggered joint assembling of universal segments is introduced; the relationship between main geometric parameters of segment structure and the minimum assembling radius of tunnel is analyzed in detail; and main segment geometry parameters matching the assembling curve radius are proposed. Secondly, the influence of different segment wedge shape quantities on assembling error is analyzed based on a metro tunnel section; and it is concluded that overlarge segment wedge shape quantity would lead to overlarge segment assembling error of straight line or slower curved line, based on which the maximum and minimum segment wedge quantity can be calculated respectively. Finally, a calculation method for recommended wedge quantity is proposed, which is compared and verified by segment selection of three metro lines. The results can provide rational suggestion for segment selection and structural design of practical engineering.