A preparation method of PCI-32765 crystalline form A, which comprises the following steps: 1) dissolving free base of PCI-32765 in a good solvent; 2) the solution prepared by Step 1) is dropwise added into an anti-solvent, stirred and added seed crystal of PCI-32765 Form A; Or the solution prepared by Step 1) is dropwise added into the suspension containing seed crystal of PCI-32765 Form A; 3) solution obtained by step 2) is continuously stirred and aged until crystal transformation is completed, then the crystal slurry is obtained; 4) crystal slurry in step 3) is filtered, washed, and dried to obtain the powder of PCI-32765 Form A. The preparation method of crystalline Form A provided by the present disclosure is a simple process and can be easily controlled, scaled up stably and conducted reliably. The process has high yield, good impurity removing capacity and is environmentally friendly. In addition, Form A provided by the present disclosure can be stably stored, and the hygroscopicity and solubility of F
