Conventional multi-transmitter-based microwave computational ghost imaging (MCGI) system has been suffered from radiation source error due to the limitation of unit performance in array. Radiation source error can cause the inaccuracy of reference radiation field in MCGI, which will reduce the reconstruction quality of target image. In this paper, a detailed error analysis of radiation source in MCGI system is conducted. The relationships among radiation source error, reference radiation field, and imaging results are determined. Further, to mitigate the influence of radiation source error and other problems in conventional MCGI systems, such as high cost, complex design and implementation, and the interference between array elements, an improved MCGI method based on a broadband polarization-sensitive-metasurface is proposed. The metasurface in this work can modulate incident signal and distribute reflected signal randomly in space. Therefore, by changing the polarization angle of radiation signal, a time-space independent signal is produced, which can achieve better detection effects on the application system. A series of simulations and experiments are performed to validate the analysis results and evaluate the proposed method’s performance. The results show that target information can be effectively obtained by the proposed method.