Due to the upcoming demands of the next-generation electronic devices with low-energy consumption, high storage density and high write-read speed, multiferroics have attracted great interest for the last decades. Among the natural and artificial compounds, BiFeO3
(BFO) is one of the most promising materials due to its high ferroelectric and antiferromagnetic transition temperature. In this article, we first give an introduction about crystalline, polar and spin structures of BFO, and how the spin and polar can couple with each other in the ground state and highly strained states. Based on this, we discuss the strong magnetoelectric coupling in BFO-related systems at reduced dimensions (e.g. heterointerfaces, domain walls, and phase boundaries). Finally,we briefly describe the magnetoelectric coupling in self-assembly BFO-based nanocomposites.With this multiferroic model system we are able to better understand the newly observed quantum phenomena in ferroic materials, and thus design and synthesize artificial superstructures by using advanced epitaxial techniques.The reversible control of the electric, magnetic and elastic order parameters is promising for possible applications in future electronic and magnetoelectronic devices.