Molecular Dynamics simulation was carried out to study the glass transition and crystallization in the metal-metalloid binary system with pair-wise potentials. The results show that a repulsive potential between metalloid (small) atoms increases the glass forming ability. The observation is consistent with the recent theory of bulk metallic glass formation through local glass transition and nano-glass formation. The theory predicted that the compositional short-range order (CSRO) prevents the small atom pairing so as to increase the glass forming ability (GFA). The present results demonstrate the important role of CSRO in bulk metallic glass formation.