Butterflies rely on their olfaction to sense the odors emitted from nectar. During the odor tracking flight, flapping wings have been speculated to actively draw odor plumes to the antennae, an action analogous to “sniffing” in mammals. Observations have long indicated that wing beating is a critical part of active olfactory sampling for butterflies, while limited studies have been carried out to evaluate how the body and wing kinematics perturb the odor plumes structures and impact the mass transport of odorant to the antennae. In this study, we reconstructed both body and wings kinematics of a forward flying monarch butterfly’s (Danaus plexippus) based on high-speed images. Computational Fluid Dynamics (CFD) simulations were adopted here as a non-intrusive approach to investigate the unsteady flow field and odorant transport process by solving the Navier-Stokes and the advection-diffusion equations. Our results showed that the flapping motion enhanced the peak odor intensity around its antennae by approximately five times. In addition, the flapping motion extended the duration of peak odor intensity attachment near the head. A longer peak period potentially provides the butterfly with more time to process odor information.