Optical parametric amplification (OPA) is recognized as a crucial technique for mitigating signal attenuation in both fiber and free-space optical communication systems. Conventional optical amplifiers are mostly phase-insensitive, such as erbium-doped fiber amplifiers (EDFAs), which are extensively employed in fiber-optic communications system. However, the signal-to-noise ratio (SNR) and link distance of the communication system are difficult to break the bottleneck due to a 3 dB noise figure limit brought by the phase-insensitive amplification. In contrast, phase-sensitive amplification (PSA) utilizing nonlinear optical frequency-mixing shows promise for near 0 dB noise figure as well as high amplification gain. PSA is one of the most potential technologies for optimizing communication performance, extending link distance, and all-optical signal processing. Herein, we will introduce the PSA technology and look forward to its application prospects in the research field of optical communication. PSA technology mainly relies on four-wave mixing (FWM) or three-wave mixing (TWM). Nonlinear optical medium that possesses large third-order nonlinear susceptibility coefficients is considered as ideal choice for achieving FWM-PSA, such as highly nonlinear fiber (HNLF) and silicon nitride (Si₃N₄) waveguide. Typically, FWM-PSA contains two separate HNLFs for cascaded FWM. The first-stage FWM generates a phase-matched idler signal and enables energy transfer from the pump to the signal and idler when specific phase conditions are satisfied. Although the signal is amplified via the energy flow, it is phase-insensitive amplification (PIA). Then, the second-stage FWM is the critical step for PSA. The idler produced in PIA along with the pump and signal is injected in second HNLF, the PSA is achieved while the three components mutually phase-matched. The phase-match condition is satisfied to guarantee the direction of energy flow. The achievement of TWM-PSA relied on the optical medium which can provide larger second-order nonlinear optical susceptibility, such as periodically poled lithium niobate (PPLN). This process primarily employs second harmonic generation (SHG) and difference frequency generation (DFG) to amplify signal. The SHG produced a phase-matched idler which has the same frequency as the pump in cascaded DFG. Thus, the efficiency of DFG can be increased to achieve higher amplification gain. Precise control of the phase relationship between the pump, signal and corresponding idler is required to optimize gain and noise figure. Additionally, the innovation of optical material and structure can also bring beneficial effects for enhancing the performance of PSA, such as Aluminum Gallium Arsenide (AlGaAs) waveguides and graphene-based hybrid structures. By enhancing the nonlinear coefficients, these materials or structures lead to higher amplification gain and lower loss. OPA is widely considered a significant advancement in optical communication systems. PIA-type amplifier, such as EDFA, has been in development for a much longer time and has entered engineering applications. Although PSA technology is not as mature as EDFA, it is able to overcome the 3 dB quantum noise limit and has better amplification gain and noise figure. The next step for the PSA research focuses on the integrated devices, which are bringing new blood into the fabrication of laser communication terminal with SWaP (Size Weight and Power) limitation. At the same time, PSA still faces technical challenges for practical application, including the integration of PSA and photodevice, weak optical detection by chip-level devices, and the phase-matching adaptation assisted by artificial intelligence in variable communication environments. However, PSA technology plays a crucial role in ultra-long-distance communication link, massive data optical interconnections, and optical-wireless convergence. It is expected to promote the development of core components for next-generation optical communication systems. PSA has broad application prospects for increasing communication speed and enhancing its link quality by overcoming limitations in noise, bandwidth, and signal-reliability.