Abstract: Work-study is an effective way to improve the competitiveness of manufacturing industry in low investment situation.Based on 5W1H method and ECRS principle,the IE methods were used to optimize air conditioner stop valve assembly line process in DAHT company.Through the job decomposition and composition within working procedure,bottleneck procedure improvement and time measurement,production line balancing rate increased from original 68.58% to 92.35%,WIP(work in process) from 40~60 reduce to 16,and number of workers was reduced by 8~10,so that workshop and logistics was uniform and reasonable.

Key words: air conditioner stop valve, line balancing, methods study, process optimization