Abstract: The solubility parameters (including dispersion coefficient δd, polarity δp, and hydrogen bonding δh) of extraction solvents (like ketones, chlorinated hydrocarbon, ester, alcohol, and ether) and diesel oil components (n-alkanes and aromatics) were estimated by using the group contribution method. The relationship between the solubility parameters of the solvent and the extraction efficiency of nalkane from diesel oil was investigated. The results illustrated that the larger the difference between the solvent and nalkane in the solubility parameters is, the higher is the extraction ratio, for the solvents except alcohols. Nonalkane content of waxpaste removed by the solvents with a dispersion contribution (fd) of higher than twothirds was much less than that by the solvents with a lower fd.