In order to solve the safety hazards of blowout prevention during the lifting process of rod and pipe in pumping wells with a diameter of 70 mm and above, the structure of the blowout prevention and disconnection device was optimized and designed. The blowout prevention technology for big pump oil pipes in pumping wells was formed through research, and an evaluation method for the safety of blowout prevention during the process of string operation was established by combining theoretical and numerical simulation methods. Firstly, the strength of the use of the blowout preventer during the docking process was analyzed through numerical simulation. Then, a study was conducted on the strength and sealing performance of the sealing system of the blowout prevention and detachment device during the process of lifting and lowering the sucker rod. Based on the analysis of the buckling behavior of the process string during the process of lifting and lowering the sucker rod, the blowout prevention pressure limit of the blowout prevention tool was obtained, with a value of approximately 30.85 MPa. Finally, based on the stress characteristics of the process string during the pumping process, a safety evaluation method for the blowout prevention during the operation process of the blowout prevention process string was established, and a safety evaluation chart for the blowout prevention during the operation process was designed to achieve quantitative evaluation of the blowout prevention safety during the operation process. The research results of the article can provide a theoretical basis for the safety of snubbing operations.