Abstract: Taking the embryogenic callus of Carex breviculmis ’Siji’ as the test material,selecting colchicine as the inducer,and using the colchicine soaking method for mutagenesis treatment.The optimal conditions for inducing polyploidy of Carex breviculmis ’Siji’ were under different colchicine concentrations and different treatments times.The ploidy of doubled plants was identified by flow cytometry and root tip chromosome counting,and leaf stomatal characteristics and plant phenotypic characteristics were analyzed,in order to provide reference for the polyploid induction of Carex breviculmis ’Siji’ and the cultivation of new Carex varieties.The results showed that the induction rate was the highest when the colchicine concentration was 0.10% and the treatment time was48 hours,and the induction rate under these conditions could reach 65 %.Comparing the plant phenotype and stomatal characteristics,it was found that the doubled plants were significantly different from the diploid plants,which were characterized by broad leaf shape,reduced plant height,and enlarged stomatal pores.