Objective To evaluate the clinic effects of alginate impression and agar/alginate combined impression. Methods 237 patients of fixed partial denture were collected and divided into group A and group B. Group A was taken impression by aglinate impression, including 81 patients（207 abutments）. Group B was taken impression by agar/alginate combined impression, include 156 patients（392 abutments）. The impressions were observed by megaloscope, and the number of abutment, the types and number of defect were recorded. Results In the aglinate impressions, 57.0 percent of abutment had some defect. But in the agar/alginate combined impressions, 36.0 percent of abutment had some defect. There were significant difference between group A and group B in the abutment, air bubbles in cervical margin, unsharpness of the gingival sulcus and shoulders（P
