Hazards, accidents and ill management in thermal power plants have a big impact on business, whether it's due to reduced productivity, lost sales, lower staff morale, or even closure. To prevent and/or mitigate workplace injuries, hazards, accidents and to improve productivity, it is needed to establish safety culture practice in the entire management system. Use of safety signs is one of the ways for controlling hazards in the work environment. Safety signs are widely used to effectively control workplace hazards. In this research, different safety culture factors were taken from OHSAS 18001:2007 standard. The objective of this study was to assess the safety culture factors in three selected thermal power plants namely Sylhet 150 MW Combined Cycle Power Plant, Fenchuganj 90 MW Combined Cycle Power Plant and Bibiyana South 400 MW Combined Cycle Power Plant. This research work describes the key factors of organizational health and safety management system. The research also measures the existing safety practice performance of the three selected thermal power plants. The collected data were analyzed to explore research findings. Lastly recommendations were made to take corrective actions to improve existing safety culture practice in the three selected thermal power plants situated in Sylhet, Bangladesh.