Rat liver tumor models are indispensable for studying trans-arterial chemoembolization (TACE), drug delivery, and tumor biology. However, conventional techniques utilizing fluoroscopy-guided carotid or femoral access are often constrained by high equipment costs, technical complexity, and cumulative radiation risks to operators. This protocol presents a radiation-free alternative using open-laparotomy-guided transtail artery catheterization. We provide a comprehensive, step-by-step description of the procedure, beginning with standardized anesthesia and exposure of the ventral caudal artery (VCA). The core of the technique involves performing a midline laparotomy to enable direct visualization of the hepatoduodenal anatomy, allowing for the precise advancement of a 1.6 Fr microcatheter into the common hepatic artery (CHA) or proper hepatic artery (PHA) using a 0.014-inch microguidewire. Our validation study in 32 rats demonstrates that this method achieves a high technical success rate of 96.9% (31/32) with a mean procedure time of 22.5 ± 2.3 min. This technique provides an accessible, reproducible, and transparent platform for laboratories focusing on localized therapeutic evaluation and embolic biology. This method effectively lowers the barrier for establishing high-quality interventional models in preclinical research environments where advanced imaging is unavailable.