The invention discloses a method for dynamically adjusting reduction process parameters of a roll straightening machine and belongs to the technical field of metal multi-roll straightening. The method is characterized by comprising the following steps of: setting an end point at one end of the straightening machine which a metal material to be straightened enters first as a calculation 0 point, and sequentially setting 1,2,3,...,J calculation points on the metal material from the calculation 0 point, wherein a distance delta L between every two calculation points is equal to T/2; calculating yield strength sigma sj between points 1 to J by solving an equation that p' is equal to pSigma after straightening starts; calculating a reduction process parameter S2 which influences the quality after straightening through an equation that (S1,S2,..., Sn) is equal to S(sigma s1,sigma s(1-1),..., sigma s(1-n+2)) when the strength is less than (n-2)delta t, and dynamically adjusting the process parameter for straightening through a pressing system; and calculating reduction process parameters S2 and S(n-1) which influence the quality after straightening through an equation that (S1,S2,..., Sn) is equal to S(sigma s1,sigma s(1-1),..., sigma s(1-n+2)) when the strength is more than (n-2)delta t, and dynamically adjusting the process parameters for straightening through the pressing system.