Abstract:This paper studies a method to test the seed viability of Yunnan pine (Pinus Yunnanensis Franch) by the radiography with water as contrast agent. The results showed that the method can be used for rapidly testing seed viability in accordance with its germination percentage. The suitable procedure is as follows: The seeds were dried in a drier(30℃) with silica gel(SiO2) for 55 hours after the seeds were soaked in water(25℃) for 24 hours and put on a germination medium for 24 hours. The internal structure of viable seeds can t been seen on its picture or slightly seen. Based on these dead seeds and viable seeds can be determined easily.