The three-dimensional photoelastic simulating experiments to tectonic stress field of great Qiongzhou earthquake of 1605 are made. The results indicate that the maximum shear stress and principal compressive stress are mainly concentrated in the depth of about 20km where the NNW trending Tashi-Yanfeng fault is intercepsted by the NEE trending. Guangcun-Puqian deep fault. The Qiongzhou earthquake of 1605 is formed in the intercepted region. Because of the influence of the vertical force, the stress vector diagram shows obviously a feature of the fault-block type dip-slip subsidence in the east of Tashi-Yanfeug fault (a narrow belt near Dongzhai port), and a feature of the fault-block type subsidence in the north of Guangcun-Puqian fault (from Puqian bay to the south of Qiongzhou strait), respectively. The results of tests are consistent with field survey as well as the analysis and calculation based on the other data.