One of the most significant factors which determine the precision of a machine is elastic thermal deformations of the structural components. The paper describes the practical application of thermal error analysis that aims towards the reduction of thermally-induced errors for precision length measurement systems operating in non-ideal environments. Finite element analysis and experimental investigations were carried out to examine the core thermal processes and to demonstrate the existence and feasibility of the thermal modal analysis in precision line scale calibration system. Keywords: Thermal error analysis FE modelling Line scale comparator