Spatial self-phase modulation (SSPM) is a third-order nonlinear optical response, also known as optical Kerr effect. The physics mechanism of SSPM is laser-induced nonlocal electron coherence, which is a collective excitation behavior, nonlinear optical response, and emergence phenomenon. Electrons in the matters move with optical frequency driven by light field and obtain phase determined by the external field. Electrons in separated domains preserve fixed phase difference and nonlocal coherence emerges. The parallel components of diffractive light form a group of concentric conical emissions, resulting in coherence rings in the far field screen. This phenomenon is SSPM. All-optical switching can be achieved based on laser-induced electron coherence in quantum materials, functioning as a “transistor” in photonics, because it can realize using a weak light to control a strong light. This article briefly reviews the investigations towards SSPM physics mechanism, as well as its potential applications in all-optical switching, emphasizing on the new progress and microscopic mechanism of SSPM.