The invention discloses a starch grafting acrylic acid kieselguhr compound water-retaining agent and a production method thereof. The technology is completed by adopting the acrylic acid neutralization and starch pasting in one step, so the production technology is simplified. The monomer concentration is improved, so the polymer is applicable to being processed by a granulator, and the drying energy consumption is reduced at the same time. First, an adherent/surface active agent is added, so the product water absorbing rate is improved, and the granulation is smoother. The water absorbing rate of the product is 270g/h and 290g/2h, and the repeated water absorbing rate is not less than 95%. The color is white, and the strength is good.