A polymorph, a polymorph screening system, and a polymorph preparing and screening method are disclosed. The polymorph preparing and screening method includes the following steps: providing a plurality of substrates of different materials; causing an organic material to grow crystals on the plurality of substrates through solution-cooling crystallization process, so that a plurality of polymorphs with different characteristics are prepared; and screening the plurality of polymorphs prepared in the previous step to obtain polymorphs with desired characteristics.