Abstract: Brittleness index of rock is an important factor for volume fracturing design of tight sandstone reservoir. This paper presents two logging evaluation methods for brittleness index—the rock elastic parameter method and the mineral composition method, and by means of rock mechanics experiment and whole?core X?ray diffraction analysis calibration, develops conventional logging?based multi?mineral model to get the brittleness index of tight sandstone reservoir. The processing result of data from Chang?7 tight sandstone reservoir in Longdong area of Ordos basin shows that using conventional logging data to evaluate the brittleness index of rock could provide technical support for optimizing selection of“dessert”of the tight sandstone reservoir by making up the shortages in difficult study of plane distribution of rock brittleness index due to fewer wells collecting array acoustic or acoustic scanning logging data