the present invention relates to novel crystalline forms of 7 - cyclopentyl - 2 -- 7h - pyrrolopyrimidine - 6 - car boxylic acid dimethylamide , its salts , and process for preparation thereof . crystalline forms in the present invention have good stability , low hygroscopicity , good processability , easy treatability and other favorable properties . in addition , the process is simple , low cost , and has an important value for future optimization and development of the drug .