The invention discloses a method for preparing rhomb-shaped superfine calcium hydrogen carbonate from Weibei ordovician limestone. The method comprises the following steps: crushing, cleaning, drying and sieving Weibei ordovician limestone, so as to obtain 1.6mm-2.0mm particles; calcining the particles at 1000 DEG C for 60 minutes, so as to obtain high-activity lime; mixing the high-activity lime with water of 90 DEG C, so as to prepare 5.6wt% of a lime emulsion; adding the lime emulsion into a container, putting the container into an ultrasonic vibrator, adding sodium laurate into the container, introducing CO2 gas, stirring, and reacting at 20 DEG C; when the pH is decreased to 7, stopping the introduction of CO2, turning off the ultrasonic vibrator, and continuing to stir for 20 minutes; and filtering, washing, and drying and grinding solute, so as to obtain the superfine calcium hydrogen carbonate. The method has the beneficial effects that the Weibei ordovician limestone is taken as the raw material, a carbonization method is adopted, a crystalline-form control agent, namely sodium laurate is added before carbonization, a gas distributor and an ultrasonic technique are adopted during the carbonization, and the rhomb-shaped superfine calcium hydrogen carbonate with excellent performance and high added value is prepared.