Despite several decades' intensive efforts,the development of accurate protein force fields remains as a major challenge.1 There are two key issues:(1)How to obtain intrinsic conformational potentials of each amino acid residue;(2)How to effectively incorporate these conformational potentials into a force field.2 We have developed novel strategies to address the above two issues.Namely,intrinsic conformational potentials can be obtained by the statistical analysis of protein coil library,3 and these conformational features can be effectively incorporated into a force field by using residue specific torsional functions.2,4 Using these strategies,we can easily develop much improved protein force fields.These force fields can better reproduce experimental NMR J coupling constants of short peptides and full length amyloid-β peptides Aβ40 and Aβ42.They can fold a series of proteins.Preliminary applications of the force fields in protein structure refinement are also presented.