Panoramic imaging sensor operating in the Midwave Infrared (MWIR) band is an important new imaging sensor for maritime research and application. Line Spread Function (LSF) is one of the key parameters to quantitatively evaluate the image quality. The modeling analysis and testing of LSF are important for developing an imaging sensor. In the present paper, the spectral radiation observed at the focal plane array of the panoramic imaging system is analyzed. The LSF of the panoramic imaging system is theoretically evaluated and tested through canted slit-method. The test results have proved the correctness of this theoretical model. The modulation transfer function is calculated by discrete Fourier transform for LSF. Results match the system theoretical MTF well, which indicates that LSF modeling analysis method is feasible.