Magnetic spins are one of the most fundamental factors in condensed matters and play a key role in many important properties such as magnetism, multiferrotics and superconductivity. Magnetic materials have long been used in industry and daily life. The magnetic-spin related behaviors are also considered for the potential applications in spintronics and quantum computing. Two-dimensional (2D) magnetic materials, a member of the family of versatile 2D materials, are new and simple platforms for investigating magnetic-spin related behaviors. However, so far the available 2D magnetic materials, mainly prepared by mechanical exfoliation, are very rare. In this talk, I will present our efforts on the growth of various 2D magnetic transition-metal halides and chalcogenides with atomic thickness by state-of-the-art molecular-beam epitaxy technique. The atomic structures, local electronic and spintronic properties are studied by high-resolution scanning tunneling microscopy/spectroscopy and first-principles density functional theory calculations. Our study paves the way for exploring new 2D magnetic systems (including ferromagnetic, antiferromagnetic, quantum spin liquid, etc.), discovering novel spin-related behaviors in low-dimensional systems, and constructing new physical models for collective interactions in condensed matters with magnetic spins.