Qinghai Lajia site is Qinghai Minhe County Guanting basin an important Qijia culture of prehistoric settlement sites in the center, in the back 4200~3500 years, but before the period of Qijia Guanting basin plant remains analysis on this is almost a blank, the flotation system carried out at the Lajia site, the carbonized plant remains rich. Lajia flotation unearthed plant remains include carbonized wood and plant seeds in two categories, there are five different crop plant seeds, millet, millet, soybean, wheat, hemp and historical records, and the "grain" of the number is exactly consistent; in addition also unearthed some weed, through analysis, can observed number in all kinds of weeds in the panicoideae is the largest, and the number in the panicoideae in Setaria most, because the number of unearthed unearthed millet, millet and millet subfamily showed positive correlation, so that the flotation unearthed subfamilies of broomcorn millet seed is upland weeds associated; in addition, floating out a certain number of hygrophilous plants, such as the Cyperaceae, perilla and so on, but the number is very small. Through the comparative analysis, carbonized plant remains unearthed in different background unit can be drawn at the Lajia site, ash ditch has not made a refuse pit with, charcoal content sites is very low, whereas the number of charring wood part ashpit and unearthed seed remains were higher than the average, the human behavior that have different functional, and the real address as the address may be cleaned regularly, leaving no carbonized plant remains too much. But according to the comparative analysis on Flotation of the foci of charcoal and weed, fuel is likely to be the use of straw and straw, rather than wood.这样可以么?