The leaf size leaf area and leaf area measuring method of Job′stears were studied. The results were shown as follows: The
leaf length, widthand thickness (SLA,specific leaf area) of Job′s-tears varied with the varietiesand the leaf position on the main stem. The medium-upper leaves on the main stemwere usually larger and thicker than the basal ones. The value of K, thecalibrated coefficient used to calculate the leaf area with the leaf length andwidth, varied with the leaf position on the main stem too. The average K of0.727 was calculated with the two varieties experimented.There were signifficantcorrelationships between leaf area(Y) and leaf length×width(X 1 ) and length/width (X 2 ), and the regression equations of Y=-0.286+0.7305X 1 and Y=-6.928+4.9268X 2 were found,which could be used to calculate the leaf area.The curve of leaf area per plant in the all growth stage fitted in with cubic equation.The SLA and leaf area of the plants in the dry-farming field which were moistured within all growth stages were larger than those in the irrigated field keeping 3─6cm thickness of the water within all growth stages. The leaf area per plant was largely composed by the tiller leaves while the leaf area of the leaves on the main stem was largely composed by the medium-upper ones at the medium-late growth growth stage.