In this paper, the lattice Boltzmann (LB) method was used to simulate the flow and heat transfer process in porous composite phase change material (PCM) with acoustic streaming, to investigate the mechanism of heat transfer enhancement caused by acoustic streaming. The study focused on the effect of acoustic streaming at different Rayleigh number, Prandtl number, amplitude and wavelength of acoustic streaming on the flow field, temperature field, liquid fraction field, and average Nusselt number at the hot wall. The results show that acoustic streaming can enhance the fluid flow in the liquid phase region, and reduce the temperature inhomogeneity and inclination of liquid–solid interface front. The natural convection and the forced convection caused by acoustic streaming both get strengthened with the increasing of Rayleigh number, thus the influence of acoustic streaming first slightly rises and then drops. The momentum diffuses slower compared to the heat diffusion with the increasing of Prandtl number, thus the influence of acoustic streaming increases. With the amplitude of acoustic streaming increasing, the effect of acoustic streaming has a more remarkable inhibiting effect on average liquid fraction, decreasing by 1.11%, 5.09%, and 20.1% at the amplitude of acoustic streaming = 0.005, 0.01, 0.02, respectively. The average temperature and average liquid fraction show no obvious differences with the increasing of the wavelength of the acoustic streaming.