Mesophases ubiquitously form in soft matter systems. For the short-range attraction and longrange repulsion (SALR) mesophase formers, the strong frustration generically impedes the determination of the equilibrium phase behavior. In one-dimensional case this problem can nonetheless be avoided as the partition function can be calculated exactly. Here, we investigate the thermodynamic signatures of clustering of a one-dimensional SALR model based on equations of state and structural characteristics, then perform simulations to analyze the relaxation dynamics. Our study deepens the understanding for the microscopic origin of the SALR mesophase assembly, which will inspire further study of three-dimensional mesophase formers.