The invention discloses a process parameter setting method for a roll straightening machine for small-batch multi-specification plate products, and belongs to the field of plate straightening. The process parameter setting method is characterized by comprising the following steps of 1. determining the temperature difference range of plates, and determining the material yield strength and the elasticity modulus at a temperature every a fixed value; 2. determining the thickness difference of the plates, that is, a standard thickness, the maximum thickness value and the minimum thickness value; 3. constructing a straightening process description space comprising S2, SN-1, B1 and BN, and traversing all available process combinations in the space; 4. when a group of S2, SN-1, B1 and BN is given, determining the position values of N straightening rolls according to a straightening equipment structure; 5. calculating the residual curvatures for the plates with specific materials and dimensions according to the related continuous bending algorithm for roll straightening; 6. with regard to fixed-point values in different temperature ranges and fixed points in different thickness ranges, obtaining different residual curvatures C under certain process of S2, SN-1, B1 and BN; 7. determining the maximum residual curvature C in the different residual curvatures C to be the residual curvatureCR under the straightening process; and 8. replacing the straightening process to obtain a new residual curvature CR, and taking the minimum value of all the residual curvatures CR as the optimal residual curvature CF, wherein the S2, SN-1, B1 and BN corresponding to the CF are the optimal process.