RFSS is a common test method in the research and development of radar guidance systems, which overcomes the problem of the large cost of the field test to a certain extent. With the development of radar technology, the evaluation of hardware in the loop RF simulation error needs to be more accurate. This paper summarizes the current research, mainly focusing on simulation error analysis, near-field error and near-field correction, expansion of simulation object and suppression of simulation error. At present, most studies focus on azimuth error and pitch error respectively, but do not take into account the correlation of the errors in these two different angle domains. Or only the root mean square of the amplitude of the two-dimensional angle error is considered, without considering the directional distribution of the angle error.