The purpose of this study was to evaluate the effect of curing time and curing temperature on the hear - Curing of acrylic resin using ring furnace. Specimens were fabricated from 2 kinds(Laboron, Bertex) heat-cured resin. Total 200 samples were divided into 4 groups(70$^{circ}C$, 100$^{circ}C$, 13$^{circ}C$, 150$^{circ}C$) and each group was divided into 5 small groups(30 min., 45min., 60min., 75min., 90min.). A microscope(Olympus Coll Co. Japan) was used to examine a randomly selected central zone, midzone and surface for each complete specimen. The results of the experiment were as follows : 1. To obtain non-polymerzation, cure the resin for 30 minutes at 70$^{circ}C$ and 100$^{circ}C$ in a ring furnace. 2. To obtain with porosity, cure the resin for 45 minutes, 60 minutes and 75 mintes at 70$^{circ}C$ and for 90 minutes at 150$^{circ}C$ in ring furnace. Porosity appears in Laboron for 30 minutes, 45 minutes at 150$^{circ}C$ in a ring furnace. 3. Every other specimens connot get a sight of special problem with makes eye in the made surface.