Abstract: The seal of YAG-to-glass is a key technique to develop yutrium aluminum garnet(YAG) projection tube. The seal. of YAG screen to glass cone is produced using low melting glass binder. The paper presents the material for the seal and the theories such as the match between the binder's expansion coefficient and those of YAG and glass, binder's infiltration to YAG and glass,and the binder's re-crystallization.The seal techniques including the binder cream's concoction, coating and bake are also given. The experimental results show that the seal performances are good.