Abstract: The disease resistance to B. dothidea of poplar callus is elementarilly similar to that of the intact plant. The expression of poplar disease resistance in callus tissues is greatly affected by concentration of auxins and cytokinins in the medium, inoculum density and temperature. But it is little affected by inoculation methods and subcultures of poplar callus. Under certain defined conditions (MS medium with O.ppm 2,4-D and 0.2ppm KT, smaller inoculum density and temperatare 28℃) the disease resistance of level of plants is faithfully expressed in poplar callus tissues.