The reflective mirror is usually used as the end mirror or the folding reflective mirror in the laser cavity during the light transmission, while it’s be acted as the role of the beam turn-back mirror outside the laser cavity. The base material of the reflective mirror is silicon,copper,Mo. The silicon is the normal coating material and it has the advantage of low cost, strong durability and stable thermal properties. The copper is usually used in the high power CO2 laser owing to it’s high thermal conductivity. The Mo can be used in a poor condition owing to it’s high surface strength and it can bear high power without surface coating,with long life span.