In investment casting,wax mold production has a long production cycle,high mold cost,and is not suitable for single casting or small-scale production.Heat-assisted direct ink writing (DIW) based on rapid prototyping is applied to wax mold manufacturing,by which the efficiency of prototyping parts can be improved.The fuse quality is the premise to ensure the molding quality.Hence,it is significant to explore the influence of printing parameters on strand forming,which contains extrusion pressure,extrusion speed,printing speed,nozzle inner diameter and gap between nozzle and hot bed.The hydrodynamic model of DIW extrusion deposition process was established for casting wax.The effects of printing parameters on strand forming were studied.Aspect ratio and compactness were used to evaluate the strand.Based on these,the optimal matching of speed ratio v/u and gap ratio h/d was obtained.Finally,the calculation model was verified by experiments.Compared with the ideal cross section model,the proposed model can be used to predict the cross section of the strand more accurately.The results provide a theoretical basis for selecting the optimal printing parameters in DIW process for casting wax.