Horizontal gene transfer (HGT) is a way of exchanging genetic elements across species boundaries, which occurs in bacteria, fungi, viruses, protists and eukaryotic genomes, is considered to be a major diver of biological evolution. Mobile genetic elements can be exchanged between bacteria species, which can contribute to the adaption of microorganism. At present, many researches are focused on the spread of microorganism and the effect of exogeneous DNA on HGT of native bacteria, which can be used for strain improvement and soil fertility improvement. Soil in the natural environment is mostly unsaturated, and the interaction mechanism of micro-hydrological environment induced HGT is of great significance for revealing major driver of HGT and maintaining the diversity of microbial populations. In this study, donor strain of the broad-host range plasmid was used in this experiment. We propose to develop a micro-model platform with micro-hydrological environment of different water potential, coupling micro-scale in situ observation methodologies, and to investigate the dynamic changes of HGT in microcolonies under micro-hydrological conditions and the important factors influencing HGT in this process.