Restrictive relationship exists between spectral resolution, spectral range and number of pixels of traditional Spatial Heterodyne Spectroscopy (SHS). The main difference between Asymmetric Spatial Heterodyne Spectroscopy (ASHS) and SHS accelerates the space of one grating from the beamsplitter. It greatly increases spectral resolution while system parameters remain unchanged. First of all, this paper elaborates the fundamentals of the ASHS, the derived formulas of the system parameters and theoretical relationship between grating offset and the spectral resolution increases. As an important parameter of the ASHS, offset is restricted by the pixel number of short double side interferogram and the spectral resolution requirements. According to the experimental breadboard parameters of laboratory, the selection principle and the results of the offset are presented. In the case of the same device parameters, two types of theoretical performance parameters are calculated. The simulation is carried out. The results show that two of them have the same spectral range, but the ASHS has a higher spectral resolution. The relationship between resolution and offset increased consistent with theoretical calculation. Finally the ASHS breadboard is calibrated with the monochromatic light scanning method. The derived spectral range and resolution are in good agreement with the theoretical value.