The invention discloses a calcium-alumino-silicate-hydrate nano-seeds suspension and preparation method thereof. The preparation method of calcium-alumino-silicate-hydrate nano-seeds suspension includes the following steps: dropwise adding the aqueous solution of calcium source, the aqueous solution of silicon source and the aqueous solution of aluminum source to the solution of polycarboxylate superplasticizer, and adjusting the pH value to 10.0˜13.5, and continuously stirring to obtain the calcium-alumino-silicate-hydrate nano-seeds suspension. The beneficial effect in the present invention is: the calcium-alumino-silicate-hydrate nano-seeds has small particle size, good dispersion stability, and it can effectively improve the early hydration and mechanical performance of cement-based materials, and has good application prospects; the preparation process is simple, without washing, drying, ultrasonic dispersion and other subsequent processes, suitable for large-scale production.