Abstract: The mannanase manA transgene FVB mice were mated with the wild-type FVB mice to gain the F1 generation transgene mice that identified by PCR and Southern blot. Total RNA of parotid gland, sublingual gland, submandibular gland, heart, liver and other tissues of the F1 generation transgene mice were extracted to perform the RTPCR detection and quantitative real -time PCR. The result showed that manA was specific expressed in parotid and sublingual glands, and was highest expressed in the sublingual gland of the transgenic mice 302 line, certificating that manA was successfully specific expressed in the parotid gland and sublingual gland of transgenic mice. Also, the saliva and dejecta of the F1 mice were collected to detect the activity of mannanase and digestibility of nutrients in feed. The result showed that the 302 line mice had the highest enzymatic activity, digestibility of crude fat in 302 line mice was significantly different with wild-type mice, while no significant difference in digestibility of crude protein and crude fiber between them. There were no significant differentce in crude protein, crude fate and crude fiber between 304 line mice and wild-type mice.