The international crude oil price trend has a great influence on the plastic market in China. As a downstream product of crude oil, plastics are out of sync with the price of crude oil, showing an equal cycle lag. However, judging from the current market price fluctuation, this lag effect is getting shorter and shorter. The influence of crude oil price on plastic price is weakened in theory, and the fluctuation of crude oil price can be weakened through industrial chain. When the crude oil price is in the rising or falling cycle, the plastic price is often in the corresponding rising or falling cycle, which plays an increasingly obvious role in promoting the rising or falling of plastic cost.