Pyrazolone derivates are compounds that widely found in biological activity. Thus, this compound commonly used in drugs production and product synthesis. In this study, pyrazolone derivatives were synthesized by Fe3O4 nano magnetic catalyst. The nano-magnetic Fe3O4 catalyst is made from iron rust and used cooking oil. Synthesis of nanomagnetic Fe3O4 is supported by characterization analysis using FTIR, XRD, EDS and SEM. Edaravone is a pyrazolone compound synthesized with ethyl acetoacetate and phenyl hydrazine. Edaravone produces a yield of 98.55 %. The synthesis pyrazolone derivate is done by mixing edaravone and aryl aldehyde like cinnamaldehyde, benzaldehyde, and 2-hydroxy-benzaldehyde. Compounds 1 and 3 were synthesized under optimum conditions. Nevertheless, compound 2 was synthesized with optimum time and temperature using 10 % by weight of the catalyst. Compound 1, compound 2, and compound 3 yields were 48.8 %, 30.4 %, and 16.04 % respectively. The formed products were determined by TLC, FTIR, UV-Vis and GC-MS. Antioxidant activity tests were carried out using compound 1, 2, and 3 with concentrations of 250 ppm.