Disclosed are an amorphous substance of idelalisibe and a preparation method therefor, so as to obtain a no-sharp diffraction peak in an X-ray powder diffraction spectrum in the case of Cu-Kalpha radiation, expressed by a degree 2¸. The present invention also provides a method for preparing the amorphous substance of idelalissibe. The method is simple to operate and is easy to implement. The amorphous substance of idelalisibe in the present invention greatly increases the dissolvability of idelalisib and helps to increase the biological utilization degree of a pharmaceutical preparation； compared with the existing crystal form idelalisib, the solubility of the amorphous substance of idelalisibe in the present is obviously increased, and the amorphous substance of idelalisibe better facilitates the absorption of the medicine by the body, so that the medicine can better achieve a clinical disease treatment effect； in addition, under the condition of accelerated testing, the amorphous substance can keep good physical stability and chemical stability.
