In order to investigate the function of Small molecular hydrophobin protein hyb2 in biocontrol fugi Trichoderma asperellum T4, the series of primers were designed based on the known cDNA fragments of small molecular hydrophobin protein hyb2, with the total RNA and the genome DNA extracted from Trichoderma asperellum T4 as the template, using PCR method, the full length cDNA and DNA sequence of hyb2 gene finally were obtained, their accession numbers were JX014433, JX185070, respectively. The cDNA sequence of hyb2 was 321 bp in length, encoding 106 amino acids. BlastP search indicated that hyb2 shared the highest similarity 87% with Tahyd5a of T. atroviride (ABS59366). Furthermore, signalP prediction showed that the hyb2 amino acid sequence was cleaved by signal peptidase between positions 16 and 17 (AFA||AP). Pfam protein family prediction showed that Hyb2 protein belonged to hydrophobin_2 superfamily. To obtain homologous gene sequences of hydrophobin protein hyb2 from the genome databases of T. virens Gv29-8 and T. atroviride ATCC74058, the amino acids sequences of hyb2 from T. asperellum T4 was used to as queries, resulting that 9 and 8 hydrophobin sequences with high similarity were obtained, respectively. Hydrophobin proteins hyb2 shared the highest 87% and 70% similarity with hyb-a-1 and hyb-v-2, located on T. atroviride ATCC74058 scaffold 5 and T. virens Gv29-8 scaffold 22, respectively.