The real space observation of spin structures with atomic resolution is a long-time dream in magnetic imaging which was realized by the development of spin-polarized scanning tunneling microscopy (Sp-STM).   This technique provides deep understanding of the structure, electronic and magnetic properties at the surface. In this talk, I will briefly introduce the basic principles and methods of Sp-STM and describe recent discoveries of novel types of noncollinear magnetic structure on the atomic scale. In particularly, taking the advantage of Sp-STM operating in the vector field developed in our lab, the surface magnetic anisotropy is identified in various magnetic surfaces. Three systems will be discussed including antiferromagnetic Néel structure, antiferromagnetic insulator and magnetic doped topological insulator. The spatial, angle and energy resolved surface spin density shows the complexity of surface magnetism.