Moving permanent magnet linear generator has some limitations such as thermal and impact force demagnetization, and complex control strategies. To overcome these limitations one of the solution is moving iron linear generators. This paper presents the analysis of flux using FEM for moving iron linear generator. The flux density varies with peak value of 0.85 for 6/1, 0.98 for 6/2 and 1.27 for 6/4 MILGs with the movement of translator. The effect of air gap on different MILGs is studied. The FEM analysis indicates that air gap have direct impact on output of the generator. The analysis is performed to replace the moving permanent magnet by moving iron in a different applications.