Fig trees are pollinated by fig wasps, which also oviposit in female flowers. They had formed obligate mutualism in their long co-evolution process. Ficus altissima (Ficus, Moraceae) is a monoecious fig plant, both the pollinating Eupristina altissima and non-pollinating Eupristina sp. symbiosis with Ficus altissima were oviposited within the syconia. Pollinating Eupristina altissima and non-pollinating Eupristina sp were highly similar in morphology, only with a slight difference on body color, antenna, fore leg coxal comb and pollen pocket for their female wasps, no morphological differences found so far between their male wasps. Fig wasps mainly located their hosts by recognizing the chemical signal released from the syconia. Also the encounter of the mating partners is fundamental for the stability of their interaction, In this study, we applied a Y-tube (binary choice) olfactometer to test the responses of E. altissima and Eupristina sp. to fig volatiles of different developmental phase of Ficus altissima and infochemical mixture. Results showed that:(1) both E. altissima and Eupristina sp. represented significant preference to the fig volatiles of female syconia, and repelled to the fig volatiles of male flower phase syconia, indicating that E. altissima and Eupristina sp. can distinguish female flower phase syconia of Ficus altissima from the male one, and keep away from the male phase syconia in order to quickly localized its female host. Observation showed there are differences responses to fig volatiles of the other developmental phase between two wasp species. E. altissima significantly repelled to the fig volatiles of pre-female phase and post-pollinated or oviposited phase, while Eupristina sp. showed no significant preference between them, which indicated that E. altissima was able to recognize the syconia of pre-female phase and post-pollinated or oviposited phase and avoid entering into them, while Eupristina sp. can not. (2) E. altissima and Eupristina sp. also showed similary responses to infochemicals linalool, benzyl ethylene The interation of benzyl ethylene and farnesol significantly affected the choice behavior of both the two wasp species. Both wasp species repelled mix infochemicals of group A₁B₂C₂(0.5% Linalool+1% Benzyl ethylene+1% Farnesol) significantly and significantly attracted by mix infochmicals of group A₂B₁C₁(1% Linalool+0.5% Benzyl ethylene+0.5% Farnesol), A₂B₁C₂(1% Linalool+0.5% Benzyl ethylene+1% Farnesol), A₂B₂C₁(1% Linalool+1% Benzyl ethylene+0.5% Farnesol), while two wasp species showed difference responses to mix infochemical of group A₁B₁C₁(0.5% Linalool+0.5% Benzyl ethylene+0.5% Farnesol). Above all, the two different wasp species can discriminate different volatile signals, and E. altissima was more favor to the fig volatiles of their host than Eupristina sp., therefore, E. altissima was able to locate their host more accurately than Eupristina sp. The different responses of E. altissima and Eupristina sp. to the fig volatiles and infochemicals may related to the different structure of their antenna. Our result will provide a scientific basis to the studies of chemical signaling mechanism of fig-wasp mutualism.