Using frequency-dependent capacitance spectroscopy, we investigate the charging dynamics of silicon quantum dots embedded in oxide matrix through a SiO2/Si-quantum dots/SiO2/Si-substrate tunnel capacitor. Two resonance peaks both for capacitance and conductance in the inversion region are observed at room temperature, being attributed to the direct tunneling between the condu ctance band ofSi-substrate and the one-and two-electron ground-state level of th e Si quantum dot. The Coulomb charging energy of the dots is extracted from the experimental results.