Spin Seebeck effect is a key thermo-spin coupling phenomenon in spintronics, which can generate spin currents in magnetic materials under a thermal gradient, providing a new approach for developing low-power, nonvolatile spintronic devices. This paper systematically reviews the latest research progress of the spin Seebeck effect, introduces the excitation mechanism and typical detection methods of spin currents from its basic physical connotations, and summarizes the main experimental configurations, such as transverse, longitudinal and nonlocal. Furthermore, this paper compares the characteristic manifestations of this effect in various material systems, including ferromagnets, ferrimagnets, antiferromagnets, and paramagnets. And the microscopic mechanisms, including magneton driving, phonon dragging, and chemical potential driving, are discussed. Moreover, this paper explores the application potential of the spin Seebeck effect in various fields, such as magnetic valves and magnetic logic devices, and in the probing of microscopic magnetic structures. At the same time, it is also noted that signal separation, interface regulation, and a unified mechanism description remain key challenges hindering further development in this field. With the continuous improvement of theoretical models, the emergence of new material systems, and the development of high-precision detection technologies, the spin Seebeck effect is expected to play an increasingly important role in spin thermionics and next-generation information devices.