Enzymes are proteins that catalyze chemical reactions, participating in almost all processes in the cell to achieve significant reaction rates and serving a wide variety of functions inside living organisms. Here, we intended to control enzymatic activities by applying external radio frequency magnetic field (RFMF) through nanosized antenna. Ribonuclease A (RNase A), which is a relative small protein that cleave single-stranded RNA, was conjugated to magnetite nanoparticles (NP) by non-covalent interaction. The diameters of Fe3O4 nanoparticles are less than 10nm. External RFMF was applied, and the enzymatic activities of RNase A were tuned at different levels by varying the frequencies and incubation times. Comparison results by using water bath were also presented.