Application of thermoplastic lined with composite pipes in gathering and transportation of oil and gas which contains H₂S/ CO₂ has attracted a wide spread attention due to its good corrosion resistance performance. However, gas permeation in thermoplastic trends to result in liner blistering or leaking, which will bring hidden danger to pipeline operation and environment. Systematically analyzed are current situations of researches on permeability of thermoplastics at home and abroad. Unfortunately, no information on permeation behaviors and mechanism of coupled oil and gas in thermoplastics are available up to now. It is proposed that full consideration is given to the coupled effect of oil and gas, material structural morphology and external physical fields, conducted is a comprehensive and systematic research on the permeation behavior of coupled oil and gas in thermoplastics, established is a suitable permeability calculation equation of thermoplastics under the actual working conditions. Meanwhile, the permeation mechanism of thermoplastics shall be fully studied in combination with software calculation and simulation. Such researches can not only provide decision basis for estimating permeation properties of traditional thermoplastics, but also can provide reference for improving their permeation properties.