In this paper, we test two methods for obtaining the coordinate of the solar disk center for the Hard X-ray Imager (HXI), one of the three payloads onboard the Advanced Space-based Solar Observatory (ASO-S) satellite. HXI is an important means to study solar flares and other eruptions. However, due to the modulation-based indirect imaging rather than direct imaging, the position of the X-ray source on the solar disk should be determined by the coordinate of the solar disk pointed by the instrument which is provided by the solar aspect system. Therefore, the solar aspect information is of great scientific significance for the location of solar flares and the realization of multi-wavelength research to understand the physical processes of solar flares. Combined with the design scheme of the solar aspect system, a test image is first generated from the data of SDO (Solar Dynamics Observatory)/AIA (Atmospheric Imaging Assembly) 4500 \AA. Then, the binarization processing is used to obtain the solar limb and the specified area of four corners. Finally, the least square method and the four quadrant method are used to calculate the coordinates of the disk center. The preliminary results show that the least square method has a relatively stable accuracy of about 0.25 arcsec, which is less affected by random noise, and can be used as the initial values for the four quadrant method. The accuracy of the latter can be better than 0.14 arcsec, but it is easily affected by random noise. The accuracies of both algorithms are significantly better than the design requirement of the solar aspect system in HXI, which can provide reference for the practical application of solar aspect data in future scientific analysis.