Timber harvesting on steep terrain is always a challenge in terms of safety, operating costs, and environmental impact. The motor-manual, cut-to-length method is the most common in harvesting operations in the mountainous areas of Thailand. The motor-manual operations are characterized by various negative features such as high fatality rates, expensive operating costs, and low productivity. The aims of this study were to evaluate the prevailing harvesting operations, to propose new working methods and systems, and to suggest work safety improvement measures. The results indicated an extremely high fatality rate in Thailand compared to the average in other countries. Possible reasons for this may include ineffective safety regulations, inadequate worker training programs, seasonal forestry workers, and a lack of personal protective equipment. Consequently, alternative working methods have been suggested as a system. The proposed working method was intended to improve work safety, enhance productivity and reduce operating costs using by simulation to find best solution. Shifting from a cut-to-length to tree-length processing and moving forward to mechanization was introduced as alternative harvesting systems. The results showed that partly-mechanized systems would significantly improve the productivity. Potential work safety improvement measures may consist of adequate training, personal protective equipment, and technological improvement. Obstacle for implementation is the high investment for forest machines and silvicultural practices.