The invention discloses a reed phytochelatin gene PaPCS, a plant expression vector of the gene PaPCS and application of the gene to the cultivation of heavy metal-resistant plants. A method for improving heavy metal accumulation and heavy metal resistance capacities of lawn grass, namely Festuca arundinacea Tall Fescue by using the trans-PaPCS gene can be widely used for cultivating plant varieties which have large heavy metal-resistant biomass and grow fast. Through the experiment, the capacity of heavy metal enrichment of the transgenic plant is improved compared with that of a non-transgenic plant.