Investigation of iron loss in fractional slot concentrated winding (FSCW) machine due to permanent magnet segmentation (PMS) are presented in this paper. First, the numerical calculation method and four models for predicting the iron loss are given, which are named as reduced segmented (RST), equal segmented distributed (EQSDT), equal segmented centralized (EQSCT) and non-segmented Formulas (NST), they are based on the influence factors of PM content, segmentation and location. Then, the detailed comparison of the analysis, including back emf, harmonic content, iron loss and eddy-current loss on machine are described and delivers that it can reduce the loss of machine, but different structure has different effects on the iron loss due to the different ways of placement, compared with others, the EQSDT can effectively reduce iron loss by reducing harmonic content and stator yoke magnetic flux density. Numerical calculations and finite element analysis have reached consistent conclusions, and this type of analysis is also suitable for other machines.