The invention belongs to the field of outdoor sports equipment and particularly relates to a grass silk fiber and a method for preparing a simulation lawn. The invention provides the grass silk fiber. The grass silk fiber is prepared from the following raw materials: linear low density polyethylene, high density polyethylene, a functional elastic material, a color master batch, a smooth masterbatch, a nucleating agent and PPA (Phenylpropanolamine), wherein the functional elastic material is selected from one or more of TPE, TPO, TPV, TPU, TPR, TPEE and POE. The invention also provides the method for preparing the simulation lawn by using the grass silk fibers. According to the method disclosed by the invention, the grass silk fiber with a three-dimensional helical structure can be obtained by secondary stretching and setting and is novel and unique in structure; and the experimental detection shows that the simulation lawn prepared by the method disclosed by the invention has the advantages that the stiffness and the resilience of the grass silks are obviously enhanced, and diversified use demands of consumers can be met. According to the technical scheme provided by the invention, the technical defects that the simulation lawn is single in structure and the performance of the simulation lawn cannot meet the diversified use demands in the prior art are overcome.