This paper gives a theoretical study on the design method of the anti-reflection (AR) film for traveling wave semiconductor laser amplifiers (TWSLA). A two-dimensional digital integration is used to calculate the optimum film parameters and their allowable errors for TiO2/SiO2 AR film coated on the facets of the 1.3μ InGaAsP lasers. Such films are successfully fabricated by using the vacuum coating and two-wavelen th control technique. The reflectivity of the is lower than 3.9×10-4. By means of the AR film, we succeeded in achieving the direct amplifioatiaa for tbe optical signal and in increasing the sensitivities of PIN & APD detectors.