The coffee ring effect is reduced effectively and a hydrogen sensor with platinum-decorated single-walled carbon nanotubes (SWCNTs) is prepared by aerosol jet printing (AJP) technology. The stable aqueous solution of platinum functional SWCNTs is prepared by a series of chemical and physical processes and the electrode array is formed by micro-fabrication technology. The AJP process is also researched in detail including the number of printing passes and the printing distance between electrodes. Then, the functional SWCNT aqueous solution is printed on the electrode array and the response of this sensor to the hydrogen is measured carefully. The results show that a functional SWCNT sensor has excellent sensing properties toward hydrogen.