The surface morphology and nanomechanical properties of poly(styrene-b-ethylene-co-butylene-b-styrene) (SEBS) having different compositions were investigated using nanomechanical mapping measurements based on atomic force microscopy. We obtained the deformation image, true surface morphology, high-resolution Young's modulus map, and map of deviated work simultaneously in a force mapping. Such maps were successfully used to identify and characterize the composition and better understand the relationship between microstructure and properties of SEBS samples. It is found that the obtained Young's modulus and deformation values, both for polystyrene (PS) or poly(ethylene-co-butylene) (PEB) blocks, strongly depend on the microstructure that is dominated by the composition. As the PS composition increase, the modulus of PS blocks increases from 19.2 +/-2.5 MPa for SEBS (10/80/10) to 823.0 +/- 168.1 MPa for SEBS (33.5/33/33.5), while PEB's increases from 8.7 +/- 2.1 MPa for SEBS (10/80/10) to 97.6 +/- 17.8 MPa for SEBS (33.5/33/33.5). The calculated map of deviated work from elastic model will be a convenient technique to visualize the distribution of viscoelasticity. Furthermore, the reconstructed true height image reveals the true topographic feature free from sample deformation.