The effect of YBCO film characteristics on the RF properties of microstrip-line (MSL) resonators using two surface resistance Rs value types of films was investigated in terms of weak links. The films were characterized in both cystallinity and microstructure. The RF properties of the resonators were measured at frequencies of about 2 GHz. It was understood that the film samples with higher Rs at 70 K, which exhibited strong c-axis orientation, both the 90 and 45- degree angle grains in plane of the films, Y211 segregation, and porous structures show large influence on RF magnetic field dependence of normalized resonant frequency-shift Δfc/fc, compared with the lower Rs type. On the other hand, the films with lower Rs at 70 K had much stronger c-axis orientation, the 90-degree angle grains, and dense structures. Consequently, it was considered that the lower Rs type films possessed fewer weak-links compared with the higher Rs type films, suggesting that the misorientation in the higher Rs films result in weak-links.