The stability of the coating is investigated. For the hydrothermal ageing, the result of ageing of glass fiber compatible to resin with ageing of coating, it is obvious to find out that the effect of ageing of glass fiber/resin composite to IFSS is more than ageing of coating. The composites have more depressed. When the coating degraded completely, the IFSS is near to the value of bare glass fiber. Ageing in the different time with different temperature showed that ageing of micro-composite was dependent on this compatible matrix. However, ageing of coating was dependent on its structure.