Thermal property of clothing has significant impact on thermal comfort of the wearers. In an extreme working condition body releases a lot of heat and sweats in order to keep the body dry and at normal temperature these heat and sweat should be released in the environment. The thermal comfort of the fabrics mainly depends on how well it transmits heat and moisture to the environment. In this work finite element models have been developed to predict the thermal conductivity of plain weft knitted fabrics. Fabrics with different stitch density and yarn count were used in this work. A unit cell model of the fabrics developed by using the actual geometrical parameters. Material orientation of the yarn was used for assigning the thermal conductivity of each element in the yarn. Boundary conditions were applied on unit cell of the fabrics for the determination of thermal conductivity. The geometrical models of the fabrics were generated by a plug-in which was developed in Abaqus/CAE using Python script. It has been found that thermal conductivity between the predicted results obtained from finite element analysis and experimental results from an in-house developed device are highly correlated. Furthermore, the application of geometrical model in different areas has been discussed, and technique is developed for the prediction of effective thermal conductivity of plain weft knitted composite fabric.