The purpose of this study is to improve digital image technology and meet its requirements for engineering measurement. To this end, this paper studies the application of digital image technology in material mechanical property testing. Based on pixel point grey value and point-by-point search strategy, particle swarm optimization (PSO) algorithm was also integrated to optimize the correlation functions. Then, an application simulation experiment was conducted. The experimental results show that the calculated displacement obtained by the optimization algorithm is closer to the normal distribution, and the dispersion degree of the calculation results is significantly reduced. Therefore, the digital image correlation method (DICM)-based integer pixel search algorithm has certain adaptability to environmental changes, and it is more suitable for practical measurement.