New preparation method for crystal with imatinibmesylate alpha crystal form

The invention relates to a control technology for crystal form of crystal. Most particularly, the invention relates to a new preparation method for a crystal of an imatinibmesylate alpha crystal form. The preparation method comprises: heating imatinibmesylate until the imatinibmesylate is dissolved in a alcoholic solvent; carrying out decolouring through active carbon; carrying out a sucking filtration while the mixture is hot; transferring the filtrate into a refrigerator after natural cooling the filtrate to a room temperature, and performing a freeze crystallization to obtain the crystal with the imatinibmesylate alpha crystal form. The preparation method provided by the present invention has advantages of simple operation, easy crystallization. In addition, during the preparation process, the solvents adopted by the preparation method have high safety.