Oil-based drilling fluids, favored for their superior stability and inhibitive properties in complex deep oil and gas strata, is constrained by a scarcity of efficient materials for leak prevention and plugging, thereby limiting their utilization. In response to this challenge, a homogenous and stable polymer, SMHDVD, was synthesized via solution polymerization, using acrylate monomers as the primary chain and incorporating functional monomers that offer resistance to high temperatures and enhanced bonding with the formation. The impact of different concentrations (0.1%, 0.3%, and 0.5%) of the crosslinking agent divinylbenzene on the polymer SMHDVD was also investigated. In-house plugging experiments have shown that SMHDVD significantly contributes to the plugging efficacy of oil-based drilling fluid systems, with a maximum reduction in cumulative drilling fluid loss of up to 68.7%, surpassing the performance of conventional plugging materials. It was observed through comparative studies that the incorporation of a crosslinking agent diminishes the sealing capacity of SMHDVD, and an increase in the crosslinking agent's concentration leads to a decline in the polymer's plugging performance. The polymeric plugging agent developed in this research offers a novel perspective for the prevention of oil-based drilling fluid leakage, with promising prospects for practical field application.