The invention discloses a method for coating and modifying surface of inorganic paper making fiber calcium sulfate whisker, which comprises the following steps: 1) mixing the calcium sulfate whisker with a dispersant relative to 1-10% of mass fraction of calcium sulfate whisker, dispersing the calcium sulfate whisker; filtering and drying after treating to obtain the calcium sulfate whisker with high dispersion; 2) measuring water, ethanol, ammoniacal liquor and organosilicon source with set volume ratio, placing the water, ethanol and ammoniacal liquor in a three-mouth flask, performing magnetic stirring, adding a proper amount of surfactant, uniformly mixing for standby; 3) adding the prepared calcium sulfate whisker with high dispersion in the three-mouth flask filled with a mixed solution, uniformly mixing, slowly adding the measured organosilicon source by batches; and 4) stirring and modifying the prepared mixed solution at the temperature of below than 25 DEG C, subsiding for 8-10 hours, filtering, and drying under the temperature of 95% to prepare the modified calcium sulfate whisker.