With the increasing importance of safety management in chemical and bioengineering laboratories, how to quickly and accurately detect and warn dangerous behaviors is becoming a popular topic. In this study, a dangerous behavior detection method based on improved You Only Look Once v5s model and human posture estimation is proposed. It is applied to the safety management of chemical and bioengineering laboratories. First, by improving the You Only Look Once v5s model, the detection accuracy and speed are improved. Then, the detected dangerous behaviors are further analyzed and judged by combining the human posture estimation technique. Finally, an indoor personnel safety video surveillance system is developed by adopting a distributed architecture and modularized design strategy. The results validated that the precision of the improved model was 97.68%, the recall rate was 96.79%, the detection time consumed was 0.022 s, and the GPU performance was 10.1. The method can quickly and accurately detect and warn dangerous behaviors. The optimized model designed by the study has important practical application value.