We used Baodi CINRAD/SA dual-polarization weather radar data from June to March to analyze airborne biological activity in Tianjin area. The results show that there are obvious seasonal differentiation and diurnal variation of airborne biological activity in Tianjin area. The migration echoes of migratory birds detected by radar were concentrated from late February to late November, among which wetland bird activity was more obvious in summer, and migratory bird activity was particularly frequent in February and November. The time of bird echo appeared was obviously correlated with sunrise and sunset. The echoes of birds show obvious circular characteristics in the reflectivity products, and the echo intensity can reach more than 35 dBz. It can be seen from the Radial velocity product that the flight speed of birds is about 10-27 m/s; From the product of correlation coefficient (CC), the overall correlation coefficient of bird echo is low, and the correlation coefficient is mainly distributed in 0.1～0.8. From the difference reflectivity （Z_DR） products, the differential reflectivity distribution is not uniform, up to 3～5 dB. Compared to single polarization weather radar, S-band dual-polarization weather radar has significant advantages in the recognition of airborne biological echoes.