Abstract: In order to study the characteristic of filtered X ray reference radiation field, Monte Carlo method was used to calculate the primary spectrum, uniformity and scattered radiation of filtered X ray reference field which was established by Division of Radiation Metrology of China Institute of Atomic Energy, and PTW ionization chamber was used to carry out experimental measurements. The results show that the simulation result is in good agreement with experimental result, and the correctness of model and validity of Monte Carlo method in simulating the filtered X ray reference radiation field are proved. The results also lay the foundation of the following simulating research.