Abstract: Radial distribution function (RDF) is a important tool to demostrate the microstructure of noncystalline solid. It is usually get from analysising the diffraction intesity of noncrystalline solid. RAD is a integrated programe to calcualted RDF from diffraction data. The main part of programe and the main step were introduced. The radial distribution function of NiTi film with different composition were calculated by RAD. The microstructure parameter of amorphous film was obtained from the analysis of the radial distribution function. The result show that microstructure parameter of amorphous NiTi was influence by the content of Ti.