This experiment used a AGS crystal with 8*8*1mm size and 8*8*0.4mm size (Theta=39deg.; Phi=45deg.)which is commonly applied in ultrafast systems. From the curve we can see that before coating the transmittance(element size 8*8*10mm) from 1um to 8um average T>70%. After this coating aimed to use in ultrafast, transmittance from 0.8um-1um was a big increase and this data remain T>90% from 1um to 6um.