Root biomass of winter wheat in 0~30 cm and 0~100 cm soil layers was studied using root core and dig sampling method. It was found that the root core method was superior to the other with three sampling position was: 1) within the rows, 2) between the rows and 3) in an intermediate position, i.e. with one edge of the core touching the row. Wheat root biomass reaches the peak as 2.5~3.5 t/hm2 at the head sprouting stage, and is about 2.0 t/hm2 at mature stage. Root biomass under serious nitrogen shortage, water shortage and saline water irrigation conditions are generally smaller than that under feasible conditions. With salt, nitrogen and water stress, the ratio of root biomass in deep soil compartment is generally higher than free from these stress factors. But the average root biomass for each ear is, however, not necessary less than that under feasible condition. And it was even 1.5 to 2.0 times as much as those under feasible condition for wheat growth under serious nitrogen shortage condition. And it was found that root biomass in a 10 cm thickness soil compartment was about half of that in the adjacent upper compartment. As a result, the total root biomass of winter wheat could be expressed as , in which R represents the total root biomass (t/hm2), and the y1 represent the root in the 0-10 cm soil compartment.