To study the influence of different evaluation methods on the overstrength factor of partially-restrained steel frames with concealed vertical slit RC infill walls (PSRCW), a ten-story PSRCW structure located in an area with a fortified aseismic intensity of 8 was designed. The standard PSRCW was extended to 40 PSRCW specimens using the Latin hypercube sampling method, and the randomness of materials (including steel, steel bar, and concrete) was considered. The hysteretic and skeleton curves of 40 PSRCW specimens were obtained using the cyclic pushover method, and the overstrength factor of the PSRCW structure was determined by the probabilistic method at the 95% confidence level. In addition, two groups of 22 near-fault and far-fault earthquake waves recommended by the ATC-63 specification were selected to conduct incremental dynamic analysis (IDA) on the structure; the same probabilistic method was then adopted to evaluate the overstrength factor of this standard PSRCW structure. The evaluation method plays an important role in the overstrength factor of PSRCW structures. The overstrength factors of the PSRCW structure considering the randomness of materials are calculated to be 1.3 and 1.73 by the cyclic pushover method for the generalized power loading distribution mode and the uniform lateral loading distribution mode, respectively. In addition, the overstrength factors of the PSRCW structure considering the randomness of near-fault and far-fault earthquake waves are determined by the IDA method to be 2.42 and 2.45, respectively.