The invention discloses a radiation device and an array antenna based on the radiation device. The low-frequency radiation device comprises a first low-frequency radiation module and a second low-frequency radiation module, wherein the first low-frequency radiation module is subjected to -45-degree polarization and the second low-frequency radiation module is subjected to +45-degree polarization; the first low-frequency radiation module and the second low-frequency radiation module are symmetrically, orthogonally and fixedly connected; and open circuit branches for preventing high-frequency electromagnetic waves from being transmitted in the low-frequency radiation device are respectively arranged at one sides of the axial centers of the first low-frequency radiation module and the second low-frequency radiation module. With the adoption of the radiation device and the array antenna, the abnormal-frequency interference can be reduced and the receiving-transmitting performance of the antenna is improved.