The invention discloses a random pilot access method based on a grid chart. The method comprises the following specific steps that 1.a user sends an uplink data frame to a base station; 2.the base station carries out channel response estimation of a pilot frequency for the first time; 3.the base station sends an empty pilot index and a precoding random access response (PRAR) to the user; 4.the user sends the pilot frequency and the index to the base station; 5.the base station carries out channel response estimation of the pilot frequency for the second time; 6.the base station constructs the grid chart; 7.the base station carries out channel response estimation of the user; 8.the base station access the response to the user; and 9.a random access process is completed. The method solves the technical problem of low number of successful access users during the larger system load in the existing random pilot access method.