Objective To investigate the dependency of thermal expansion coefficient of DNA adsorption film on environmental conditions. Methods By treating DNA adsorption film as a macroscopic continuum film with prestrain, an equivalent composite beam model of DNA film-substrate was established to calculate the deflection of DNA-microcantilever beam under temperature loading. By adopting Parsegian’s empirical potential which described the mesoscopic free energy of DNA adsorption film, the DNA liquid crystal-substrate multi-scale deflection model, the thought experiment method and the equivalent deformation method were combined to establish the trans-scale relationship between the microstructure of DNA adsorption film and its macro-scale mechanical properties. The thermal expansion coefficient of DNA adsorption film was predicted. ResultsGiven the ionic strength, the thermal expansion coefficient of double-stranded DNA adsorption film ranged from 0.3×10-4/K to 8.05×10-4/K, and that of single-stranded DNA adsorption film ranged from 1.28×10-4/K to 9.33×10-4/K. Conclusions As a leading role in the competition of micro-interactions, the change of configurational entropy determines the dependency of thermal expansion coefficient of DNA adsorption film on environmental conditions; the thermal expansion coefficient of DNA adsorption film decreases with the increase of temperature or ion concentration or DNA packing density. These results are useful for gene detection and its regulation, and provide reference for the evaluation of tissue organ performance in tissue engineering.