To evaluate the safety and effectiveness of open superconducting magnetic resonance (MR)-guided microwave ablation of liver tumors and explore feasibility of real-time imaging sequence-guided needle insertion technique. Medical records of December 2019-May 2021 of microwave ablations of liver tumors under MR guidance in XX University Cancer Center were reviewed. Real-time imaging-guided puncture technique refers to real-time insertion and adjusting the position of a microwave applicator under a fast imaging sequence. The safety and efficacy of the procedure among the enrolled patients were assessed. Twenty-six patients underwent 27 procedures, with 30 lesions ablated (long diameter: 1.51 ± 0.81 cm, short diameter: 1.30 ± 0.61 cm). There were 20 cases of primary liver cancer and 10 of liver metastases. All lesions were identified by MR imaging (MRI), and all procedures were successfully performed using the finger positioning method for puncture sites. Five patients underwent real-time guided needle insertion techniques. Further, the microwave applicators reached the target position at once, and the entire insertion process was completed within 3 min. The completion rate of the real-time guided needle insertion technology was 100%, and 25 (92.6%) patients had minor complications. No severe complications were observed, and the technical success rate of 30 MRI-guided lesions was 100%. Finally, the complete ablation rate of the MRI-guided ablation after the first procedure was 93.1%. Open MR-guided microwave ablation is safe and effective in treating liver tumors. Furthermore, real-time imaging sequence-guided puncture technique under MRI is feasible and efficient.