In order to study the effect mechanism of molybdenum(Mo) and nitrogen(N) on lodging resistance of wheat,a randomized block design was used,two varieties winter wheat 97003 and 97014 were applied as materials,four N levels (N 0,120,210,300 kg/hm2) and 3 Mo levels (NH4)2MoO4 0,0.75,1.50 kg/hm2) were set to compare and analyze the changes of stem morphological characteristics,basal stem node thick cell wall components and stem mechanical characteristics of wheat under different Mo and N ratios. The results indicated that:(1) Under the same N and Mo levels,the distance from break to top and bending moment of Mo low-efficiency variety 97014 were higher than Mo high-efficiency variety 97003; compared with no N application,the fresh weight and bending moment of above-ground parts of two wheat varieties could be improved at three N levels,especially 210 kg/hm2 N was obvious,and N application has a significant effect on the section coefficient and bending stress. At N 0 and 210 kg/hm2,the breaking moment will increase with the increase of Mo application;(2) The basal node length of wheat variety 97003 was higher than that of wheat variety 97014 under all Mo and N fertilization levels,while the upper node length and ear length were lower than that of wheat variety 97014; the outer diameter of long axis and the inner diameter of longaxis and ear length of wheat Mo efficient variety 97003 increased with the increase of N application level in addition,the outer diameter and inner diameter of long axis,basal stem length and ear length of wheat variety 97014 increased with the increase of N application level; (3) With the increase of N application rate,the nonstructural carbohydrate of wheat stem decreased significantly,and the application of (NH4)2MoO4 0.75 kg/hm2 in efficient wheat variety 97003 can reduce the amount of nonstructural carbohydrate in wheat stem; (4) The cellulose and lignin content in the base of two wheat varieties were different. The cellulose and lignin contents of 97003 wheat variety with high Mo efficiency were basically unchanged under different treatment. The cellulose content of wheat variety 97003 with low Mo efficiency was increased by applying (NH4)2MoO4 1.5 kg/hm2 under four N levels. The lignin content of basal internode decreased when 0.75 kg/hm2 (NH4)2MoO4 was applied at 210 kg/hm2 N and 120 kg/hm2 N. The optimal combination of the main physical properties of the two winter wheat lines under different Mo and N application rates were different. The short and thick basal internode,large stem wall thickness,increased total amount of structural carbohydrates and good stalk plumpness were the direct reasons for the high bending resistance,small lodging index and enhanced lodging resistance of winter wheat.