It is a research subject that has attracted a wide concern and study for a long time to find a suitable trading point of stock. From the views of big data and quantization technique, the paper tries to propose an approach, through the form of algorithm, based on big data analysis and linear weighted moving average curve, to find the point of buying stock, so that the trader would like to achieve the expected profit with a higher probability; and makes the digital experiment to further explain the approach and verify its performance. This work can promote the development of big data research and quantization technique, and can also provide a certain reference method for the trader making the technology analysis of the trade.