Abstract: When prestressed tendons were being tensioned in prestressed concrete frame structures,lateral restraints of columns brought about the loss of designed pre_added axial force.the loss induced designed pre_added axial stress not to be reached in beams,and would result in secondary shear and secondary moment in columns,and in beams too.In over_long and over_wide prestressed concrete frame structures with obvious lateral restraints,if the influence of lateral restraints of columns on the transfer of pre_compressive force in beams was not thought over rationally,not only the control of cracks could not be satisfied,but also the computation of carrying load capacity was not safe.Computational models of secondary interior force were built up for different tensioning order,and computational formulas were derived.Some methods were put forward for rational structural design.