Natural infochemicals may largely affect the trophic transfer of microplastics (MPs) in ecosystems but such inforchemical effect and mechanisms are poorly understood. Here, a daphnids-zebrafish freshwater microcosm was designed to elucidate whether and how an algae-derived inforchemical, dimethylsulfoniopropionate (DMSP), affects the ingestion and transfer of MPs. Daphnids fast accumulated DMSP and MPs from water, DMSP in daphnids was mainly enriched from the DMSP in water but not from MPs. DMSP did not change the MP ingestion by daphnids. A low concentration of DMSP (<5 nM) increased ingestion of daphnids by zebrafish, while a high concentration of DMSP (>50 nM) did not increase ingestion rates. Interestingly, the MP ingestion by zebrafish in the 0.5 and 5 nM DMSP treatments were 2.06 and 1.69 times that of the control, respectively. This suggest the DMSP at environmentally relevant concentrations may promote the trophic transfer of MPs in freshwater ecosystem via olfactory traps.