Abstract: By the method of 15N tracing technique, combined three different soil fertility with two different irrigation quantity, the synthesis effect of nitrogen balance in wheat production was studied in cement-pool cultivation. The result showed that: (1) The absorption efficiency of nitrogen fertilizer varied from 39.08% to 53.08% in different treatment, N remained in soil ranged in 21.80%~33.59% and losses in 18.81%~34.62%. Above data showed that nitrogen balance in wheat production system could be regulated effectively in large scale with different combination of soil fertility and irrigation quantity. (2) The amount of total N accumulated in wheat plant and which derived from soil increased, but the proportion resorted in vegetative organs increased and the proportion distribution in grain decreased significantly with increase in soil fertility. The order of N amount derived from fertilizer respond to soil fertility was as follows: medium fertility >high fertility >low fertility, the loss efficiency was low fertility >high fertility >medium fertility and there were no significant difference in residue rate of N fertilizer. Based on above analysis, it could have negative effect on absorption efficiency of nitrogen fertilizer with soil fertility increased gradually after medium level achieved, but it could effectively reduce dependence on nitrogen fertilizer. (3) Irrigation quantity increasing could enhance the capacity to absorb nitrogen on different fertility, but the synergistic effect of irrigation on soil nitrogen uptake was more than fertilizer nitrogen uptake, it also increased loss efficiency of fertilizer nitrogen, decreased residue rate in soil and distribution rate in grain. (4) Economic yield, biological yield and soil A values increased and harvest index decreased with soil fertility enhanced and irrigation quantity increased, protein content of grain increased with soil fertility enhanced and decreased with irrigation quantity increased.