Abstarct: The fungus Trametes versicolor (L.: Fr.) Pilát, which is also known as the rainbow, is the cause of white rot and has been introduced as the first producer of laccase. Due to its many environmental and industrial applications, the laccase enzyme has attracted the attention of biotechnology researchers to increase its production and decrease the final price. In order to investigate the production and activity of laccase enzyme in the rainbow mushroom, the native isolate was collected from forests in Guilan province, then identified and the ability of laccase enzyme production in the presence of different plant hosts, including sawdust and wood chips of oak (Quercus castaneifolia), poplar (Populus deltoids) and pine (Pinus teada) was evaluated. Also, the effect of copper as inducer on the enzyme production was investigated in vitro. Afterwards, the antifungal effect of its extract on important plant pathogens (Macrophomina phaseolina, Fusarium spp., Rhizoctonia solani, Sclerotinia sclerotiorum, Botrytis cinerea) was investigated. The results showed that adding the host plant substrate to the culture medium has increased laccase enzyme production, and among this, oak sawdust substrate had the greatest effect (double compared to the control) in increasing laccase enzyme production. Also, the effect of the extraction time on the amount of enzyme showed that the 5-hour extracting cycle resulted in the highest amount of laccase enzyme (18.97 units/l). Furthermore, the addition of different concentrations of copper to the culture medium showed that copper increases the production of laccase enzyme and the highest amount of enzyme production (92.04 units/l) was obtained when the concentration of 3.5 mM CuSO4 was used in the presence of oak host sawdust. Results of antifungal effects also showed that the alcoholic extract of rainbow mushroom has antifungal activity, which increases in the presence of the plant host. The alcoholic extract of this mushroom had the ability to inhibit mycelial growth of fungal pathogens such as F. acuminatum (18.28%) and R. solani (9.84%). Also, concentrations of 25 and 30% of culture filterate could prevent the growth of plant pathogenic fungi such as F. solani, Botrytis cinerea and F. acuminatum. These results show the possibility of using mextabolites and extracts of this mushroom in the biological control of plant pathogens; that its utilization requires supplementary researches. In the end, it can be mentioned that the use of oak sawdust substrate along with copper inducer can have a significant effect on the production and activity of laccase enzyme.