The liquid closed tunable lens has been designed and made based on polyd imethylsiloxane (PDMS).The appropriate structure of lens is decided accordi ng to mathematical analysis in Matlab software and structure simulation of PDMS film deformation in ANSYS software.In preparation process,f irstly,the chamber of lens is fabricated with an SU-8mold;secondly,cover-film is made by using the mi xed PDMS,and then two parts of lens are bonding together after surface treatment.After liquid injection and second ary bonding,the whole process was accomplished.Finally,surface deformation and focal distance of the lens are tes ted with a testing device,and according to the test result,the curve between focal distance and magnetic flux density is plotted.In this process,with the magnetic flux density changing from 200mT to 600mT,the focal distance ch anges from 22.0mm to 20.2mm under the electromagnetic loads.Results show that fabricating tunable lens with this method can simplify processing sequence,lower production cost,and reduce the whole structure volum e.Moreover,the finished product has controllable focal distance and great sealing property,so the surrounding w ill have minimal effect on the performance of lens,which may open new possibilities in medical service,optica l testing and other fields.