We studied the effect of host marking pheromones (HMP) and experiences of female wasps on oviposition behavior of Trichogramma ostriniae (Peng & Chen). The results indicate that female wasps deposit HMPs on the chorion of host eggs with her ovipositor near the end of egg-laying process. Na ve females do not posses the ability for recognizing the marking pheromones and have to obtain the ability though the learning process, in which the wasp inserts her ovipositor into a host egg to determine whether the egg has been parasitized followed by antennal drumming on the exterior . Once the learning process is completed, the female wasp will be able to discriminate between parasitized and unparasitized hosts and reject a parasitized egg by simply drumming on the exterior of the egg. Learning plays an important role in reducing initial rejection time when an unsuitable host is encountered. Female wasps of T. ostriniae can quickly learn to associate the presence of a HMP on host egg chrion with the internal status of the egg. The results of this study has enriched the ecology theory and provided the scientific basis for the better application of T. ostriniae in biological control.