Polarization switching induced by local mechanical force via flexoelectric effect has recently attracted great attention since it may enable applications in which memory bits are written mechanically and read electrically.When applied an electric field,the mechanically written domains however show lower remanent polarization and higher offset bias of the hysteresis loops which are detrimental to the information writing and reading of ferroelectric memories.Here,the strain tunability of remanent polarization and offset bias of the hysteresis loops of mechanically written domains is numerically investigated by using a multi-field coupling model of flexoelectric.The polarization response of mechanically written domain in film with different misfit compressive and tensile strains is examined.It is found that the remanent polarization of the mechanically written domain grows significantly with increasing compressive misfit strain while the offset bias of the hysteresis loops reduces remarkably with increasing tensile misfit strain.Our work suggests that misfit strains imposed by the substrates have the power to tailor properties of mechanically written domain for non-volatile memory application.Our study provides some guides on the application of mechanically writing memory bits in ferroelectric memories.