The crystal structure and phase transition of (1-x)Pb(Yb1/2Ta1/2)O(3)xPb(Fe1/2Ta1/2)O-3(PYT1-xPFTx) solid solutions for 0less than or equal toxless than or equal to0.25 have been studied by X-ray diffraction and the dielectric constant measurement. From the analysis of the superlattice structure of the (PYT1-xPFTx) solid solutions, it is found that the crystal structure of PYT1-xPFTx changes from the monoclinic to the pseudocubic as x increases beyond x=0.20 at room temperature. In the composition region (xless than or equal to0.20), the dielectric constant vs. temperature curve exhibits a sharp normal paraelectricantiferroelectric phase transition. For xgreater than or equal to0.05, dielectric dispersion at 177degreesC which is the secondary phase transition point of PYT disappears. Beyond x=0.20, the dielectric constant vs. temperature curve shows significant broadening, but no relaxor behavior has been detected.