Fungal endophytes do not harm the plant when they live inside the host. Previous studies also showed that the content of some secondary metabolites are correlated to the endophytes within plant. Whether such a mutualistic symbiosis system could be implanted to bio-engineering or not will be an important and exciting problem. Here a fungal endophyte was co-cultured with the cell suspension of Acer ginnnala which is rich in gallich acid to test the problem above. The results showed that the growth of plant cells and the cell vitality decreased after the endophyte added, while gallic acid content increased. It was preliminarily determined that there is a partial competition relationship.