The patternless casting manufacturing (PCM) technique adopted two nozzles to spray the binder and the curing agent separately into the dry sand under the control of a computer. In the PCM technique, the resin content of sand mold is mostly determined the quality of the final casts. In this paper the content of the binder droplets in sand particles is analyzed in detail. Thus it provides the theoretical basis for these process parameters such as scanning speed, layer thickness and so on. The results of experiments well verify the analysis.