We have investigated correlation between luminescence property and particle size of nanocrystalline silicon (nc-Si) fabricated by controlling Si concentration in an amorphous SiOx (a-SiOx) films. The Si concentration in the a-SiOx film was increased with increasing a RF power and lowering a gas pressure. The increase of Si concentration led to expansion of the particle size of nc-Si. The particle size of nc-Si was varied from 1.8 nm up to 3.5 nm for the sample introduced the Si concentration from 0.7 % up to 9 %. The luminescent color from nc-Si grains, which differs in size, showed a red/green/blue lights.