Abstract: A microstrip resonator was designed with theoretical calculation and HFSS simulation. The feasibility of the three-dimensional confined structure was identified with the comparison of the HFSS results with or without the existence of three-dimensional confined structure. The measured values of resonance frequency and S₁₁ were 2. 5 GHz and -17. 94 dB, respectively. This microstrip resonator successfully induced microplasma with three-dimensional confined at frequency of 2. 5 GHz, the wide pressure range from 30 Pa to atmospheric, and the input power range from 0. 7 to 6 W. At 7. 5×10⁴ Pa, a line profile of the hydrogen Balmer β line was detected with the spectrometer. And the electron density was 5. 54×10¹³ cm^-3, the value was accorded with the typical values of electron density of microplasma source.