Digital Fingerprinting is a technique for the merchant who can embed unique buyer identity marks into digital media copy, and also makes it possible to identify “traitors” who redistribute their illegal copies. At present,the fingerprinting scheme generally has many difficulties and disadvantages for large-size users, involved in code construction with shorter length and effective traitor-tracing. To resolve these problems, this paper presents the definition of Fingerprinting Information Code and a practical construction method by composing of convolutional codes and common fingerprinting codes based on Boneh-Shaw model. Its decoding algorithm is presented by improving Viterbi algorithm through introducing the idea of ‘Optional Subcode Set’. The security and performance are proved and analyzed by theory and example. The results indicate that the proposed scheme has shorter information encoding length and achieves optimal traitor searching in larger-size users.