The effect of solvent polarity in the synthesis of monoformyltricyclodecane (MFTD) and diformyltricyclodecane(DFTD) by hydroformylation of dicyclopentadiene (DCPD) were investigated on the Co-Rh /Fe_3O_4 catalyst modified with PPh3. The results showed that the polar of solvent has significant influence on the reaction rate and the target product selectivity. The generation rate of MFTD increased with increase of the solvent polarity. However, the formation rate and selectivity of DFTD increased at first, then decreased with a higher solvent polarity; Up to 72% DFTD selectivity could be obtained with 5. 4 polarity acetone as the solvent.