The thermal analysis is necessary in design process of new electric motor. During motor design process is necessary to know temperatures of induction motor’s (IM’s) construction parts. The calculated temperatures in all motor parts should be lower than critical temperatures. This paper deals with free-dimensional (3D) transient thermal analysis of small squirrel cage motor/induction motor. The design of new IM is based on dimensions of permanent magnet synchronous motor (PMSM). In the initial stage of motor's design the coupled finite element analysis (FEA) method gives enough valuable results of the IM's temperature rise. Coupled thermal analysis is made through computational fluid dynamics (CFD) and finite element method (FEM). The CFD model of IM is used for calculate boundary condition such as heat transfer coefficient. Results of CFD model are implemented in to transient thermal analysis as boundary condition.