A terahertz asymmetrically coupled resonator (ACR) consisting of two different split ring resonators (SRRs) was designed. Using finite difference time domain (FDTD), the transmission of ACR and its refractive-indexbased sensing performance were simulated and analyzed. Results show that the ACR possesses a sharp coupled transparent peak or high quality factor (Q), its intensity and bandwidth can be easily adjusted by spacing the two SRRs. Furthermore, the resonator exhibits high sensitivity of 75 GHz/RIU and figure of merit (FOM) of 4.4, much higher than the individual SRR sensors. The ACR were fabricated by using laser-induced and chemical non-electrolytic plating with copper on polyimide substrate, the transmission of which measured by terahertz time-domain spectroscopy system is in good agreement with simulations.