Abstract: Smoothed Particle Hydrodynamics (SPH), as a meshless numerical method, has been widely used in the simulation of free-surface flows due to its inherent ability to deal with large deformations, topological variations, and free-surface fragmentation. In the numerical simulation of SPH, tension instability caused by negative pressure and uneven particle distribution are often encountered, which can lead to the creation of unphysical gaps near the free surface, thus affecting the stability and accuracy of the calculation. Particle Shifting Technology (PST) has been widely introduced as an effective improvement scheme to alleviate the above problems by redistributing particles and maintaining spatial homogeneity, but several existing PST improvement schemes still face problems such as high computational complexity and non-smooth free surface. In order to solve these problems, the article proposes an improved particle displacement technique (NPST) within the framework of weakly compressible SPH, based on the IPST proposed by Wang et al. The method solves the problem of non-physical gaps in the vicinity of the free surface while compensating for the lack of the free surface by controlling the effect of the free-surface particles on particles in the vicinity of the free surface to solve the problem of free-surface irregularity. In order to verify the stability and validity of the NPST, the article performs numerical simulations of three classical free-surface flow problems, namely, numerical wave-making, square droplet rotation, and droplet oscillation. The results show that this improved particle displacement technique not only retains the excellent characteristics of the traditional PST, but also the algorithm is simple and easier to implement, which can improve the computational efficiency to a certain extent. Meanwhile, by comparing and analyzing the results with those of IPST, it is further shown that NPST can effectively solve the problem of inhomogeneous distribution of particles near the free surface, thus improving the computational accuracy.