Normally it is difficult to obtain full-length cDNA sequence of novel genes. More and more expressed sequence tags(ESTs) have been obtained since the start-up of human genome project. Powerful system is badly needed for data mining on these EST sequences. Based on a personal computer coupled with Linux operating system and EST database, the Blast software and Phrap software were used to construct a platform for in silico elongation of ESTs in our lab. The performance was tested using 11386 EST sequences and 511 partial-length cDNA sequences. Results demonstrated that 8373 EST and 389 cDNA sequence were elongated using this system. Thus the platform seems to be a fast way for full-length cDNA sequence cloning of new genes.