Abstract: Antennas of female and male Diadromus collaris (Gravenhorst) (Hymenoptera: Ichneumonidae) were observed by scanning electron microscopy (SEM) to specify the distribution and morphology of antennal sensilla. Five distinct types of sense receptor on the antenna of D. collaris, including sensilla trichodea, sensilla chaetica, sensilla basiconica, sensilla placodea and sensilla coeleoconica were found. Among them, sensilla trichodea was divided into two morphological sub-types which existed on the antennas of male and female D. collaris. More sensilla trichodea were observed on the antenna of female than male. Six sub-types of sensilla basiconica were identified, among which the types Ⅱ was only found on the antenna of male, while type Ⅲ, Ⅳ, Ⅴ and Ⅵ were only found on the female antenna. More sensilla placodea were found on male antenna, in contrast, sensilla coeleoconica was only found with fewer amounts on female antenna. We did detailed descriptions on the five types of antennal sensilla and compared them with antennal sensilla of other parasitoids.