We present the beam pattern measurement of the Tianlai Cylinder Pathfinder Array. As it is a pure drift-scan instrument, we exploit the North–South (N–S) motion of the Sun to demonstrate that the primary beam is factorizable. Leveraging this property, we decompose the primary beam into independent East–West (E–W) and N–S components. Using the Sun as a calibration source, we obtain the E–W beam profiles at various elevations, applying normalization to eliminate the effects of solar activity. Subsequently, we simulate the observed signals using a sky map model to derive the best-fit N–S beam. The results of this work are consistent with previous expectations.