The invention provides a method for growing calcium sulfate whiskers from fluorgypsum slag and the calcium sulfate whiskers, and relates to the field of preparation of calcium sulfate whiskers. The method comprises the following steps: taking the fluorgypsum slag as a raw material, grinding the fluorgypsum slag, and mixing the fluorgypsum slag with water to obtain slurry; adding soluble carbonateinto the slurry, stirring and reacting, and then filtering to obtain a first filtrate and a first filter residue; adding an acid solution into the first filter residue, stirring and reacting, and thenfiltering to obtain a second filtrate and a second filter residue; mixing the first filtrate and the second filtrate to obtain a calcium sulfate colloidal solution; and adding a crystal growth promoter into the calcium sulfate colloidal solution, standing for reaction after hydrothermal reaction, and drying to obtain the calcium sulfate whiskers. By the method, the waste fluorgypsum slag can be recycled to obtain the calcium sulfate whiskers with high added value. The preparation method is stable and reliable, and the obtained calcium sulfate whiskers are high in purity, large in length-diameter ratio and wide in market application prospect.