In this dissertation, we study multiple nonequilibrium many-body systems from different aspects. We begin with a brief introduction to nonequilibrium system and general discussions of terminology. In Chapter 2, we study locally scrambled quantum evolution and develop a novel formalism to describe entanglement dynamics. In Chapter 3, we examine quantum quench across quantum phase transition in the presence of decoherence. We found a new scaling law in strong decoherence limit. In Chapter 4, we investigate multiple one-particle probes to diagnose the properties of steady states under dissipative and decoherent dynamics.