Abstract: The charge and spin degrees of freedom of electrons are at the heart of modern electronic devices. With the development of 2-dimensional (2D) materials, especially 2D transitional metal dichalcogenides (TMDCs), another degree of freedom ─ the energy valley ─ has attracted great interest. Due to the strong spin-valley coupling in TMDCs, the spin can be easily controlled and detected through the valley degree of freedom, and vice versa, providing novel routes to study spins and valleys. In this article, we first describe the valley degree of freedom and the physics of strong spin-valley coupling in TMDCs, then review recent theoretical and experimental work on coupled valley and spin manipulation through optical circular dichroism and spin injection. Finally, the current progress and future prospects are summarized.