Provided are a functional reinforcing filler and a method of preparing the same, and more particularly, a functional reinforcing filler including inorganic particles having a surface modified by an organic silanepolyol obtained by hydrolyzing an organic alkoxysilane compound and a method of preparing the sane. The functional reinforcing filler has hydrophobicity and reactivity. If the functional reinforcing filler is used to prepare rubber, a coupling agent is not required, and the rubber does not emit volatile organic compounds (VOCs). In particular, a tire prepared using the functional reinforcing filler may have low rolling resistance and excellent wet traction.