The process condition of modification starch used in mounting with α enzyme is discussed;the solid condition is 10%.Through experiment, the best process condition is testified,keeping temperature at 60℃ for 25min,pH at 6.6,the usage of α enzyme is 11U/g to the usage of starch and the viscosity of the starch is 2.3mPa·s.Compared with wheat flour,enmymolysed starch has better stability and mildew resistance.Besides,it can also improve the strength of xuan paper,favourable for long term conservation of calligraphy and painting.