Objective Random allocation concealment is important in ensuring high-guality randomized controlled clinical trial.In this paper , we aimed to design a more convenient and effective two couplet random allocation method through improving the random allocation concealment technology which uses the envelope method . Methods According to the randomized sequence , a two-couplet random allocation should be prepared for every subject and bound into a book in order , which named random assignment book with cover and instructions .The first couplet is to collect the enroll information and the second couplet is to show the allocation informa -tion.The serial numbers of the two couplets which around sealant are the same , and leave blank at the same areas of the two couplets for signing the enter information .The content of the first couplet can be completely copied to the second couplet .In order to avoid expo-sing the allocation information in advance , the back of the second couplet should be black-printed. When the subjects are sure qualified, the researchers selected the corresponding two couplet in a sequential order .Exposing the allocation infromation in the second couplet, and the subjects will be allocated to the group designated on the second couplet .This random allocation book should be entrusted to professional printing mechanism ,printing according to the random assignment sequence table and in the strict quality control .For the multicenter clinical trials , it can be printed in parts . Results The method has been implemented in nearly ten randomized controlled trials and obtained the consistent high praise . Conclusion The random allocation book method is easy to produce , simple operation and convenient in monitoring , which can effectively achieve the random allocation concealment in a clinical trial as well as having a sig -nificantly practical value in ensuring the quality of randomization .