Fe3O4@THAM-Mercaptopyrimidine nanoparticles, as eco-friendly and inexpensive compounds, catalyzed the synthesis of 1,8-dioxo-octahydroxanthenes efficiently through pseudo-three-component condensation of aromatic aldehydes and dimedone and the synthesis of polyhydroquinolines through via a four-component condensation of aromatic aldehydes, ethyl acetoacetate, dimedone, and ammonium acetate. The chemical structure of Fe3O4@THAM-Mercaptopyrimidine as a new nanocatalyst was completely confirmed with different techniques like FESEM, EDS, XRD, TGA, VSM, and FTIR analyses. This method has some benefits including low-temperature synthesis, good yields, short reaction time, easy work-up, and the use of a highly recyclable nanocatalyst.