The invention discloses a method of testing the frequency static characteristic coefficient of a grid under the condition of large non-grid disturbance, comprising the following steps: (1) exiting from the AGC of a grid-connected unit in a grid and other secondary frequency modulation control operations; (2) selecting a test unit serving as grid power disturbance in the grid: gradually increasing/decreasing the output of the test unit, and after each increase or decrease in output, stabilizing the output for a period of time to form a new steady-state frequency of the grid through adjustment; and (3) after the test, analyzing the total output and steady-state frequency of steady operation condition points of the grid in the test process, drawing a relational graph of the total output of the grid and the steady-state frequency of the grid, and getting a frequency static characteristic relation curve of the grid in different frequency bands through data fitting, wherein the slope of the curve is the measured frequency static characteristic coefficient of the grid. The problem that the existing grid frequency static characteristic coefficient test method is easily affected by secondary frequency modulation due to high restriction and uncertainness or is of high test difficulty and high security risk is solved.