The imaging performance of type I holographic concave gratings would be seriously deteriorated by the recording parameters error during fabrication of the gratings. A numerical simulation was made for analyzing the effect of recording parameters error on imaging performance of the grating. The following conclusions can be obtained from the simulation results. Firstly, the larger the difference between errors of the two recording distances, the worse the imaging performance becomes. Secondly, the recording angle error remains very small because the recording distances for type I gratings are usually very long. The image widths would not change significantly. But the locations of the images would change because the grating constant is different from the desired value. Finally, it is very important to make the curvature radius as close to the namely value as possible, because the radius error would greatly deteriorated the focusing abilities of the gratings. This study can give theoretical guidance to the fabrication for type I holographic concave gratings and reduce the alignment difficulty for the Rowland circle spectrographs.