Adding calcium silicate hydrate seed-polycarboxylate ether (C-S-Hs-PCE) to cement-based materials can effectively improve the early strength. C-S-Hs-PCE can provide nucleation sites for the formation of a hydration product C-S-H gel, effectively promoting the generation of the C-S-H gel, and accelerating the process of cement hydration. The acid-ether ratio is an important structural parameter of comb-type PCE molecules, having an impact on the synthesis and early strength enhancement of C-S-Hs-PCE. This paper investigated the effect of acid-ether ratio on the particle size of C-S-Hs-PCE and the early strength of cement-based materials by using dynamic light scattering (DLS) particle size analysis, total organic carbon analysis, X-ray diffraction, low-field time-domain nuclear magnetic resonance, scanning electronic microscopy, isothermal calorimetry, and compressive strength tests, respectively. The results show that the C-S-Hs-PCE formed at a high acid-ether ratio PCE has a smaller particle size, which is more conducive to promoting the hydration of the silicate phase and the generation of calcium hydroxide and C-S-H gel, thereby accelerating the hydration of the paste, reducing the total porosity of mortar, and improving the early compressive strength of mortar, especially within 24 h.