An anti-TNFR2 antibody, 1C3, was obtained via unbiased screening by detecting efficacy using humanized mice. 1C3 binds to the CRD3 AND CRD4 domains of TNFR2 without blocking the binding of TNFα. Compared with TNFα-blocking antagonists, 1C3 showed a greater effect in reversing the inhibition of Tregs on CD8+ T cell proliferation. Depletion of Tregs via ADCC and Teff/Treg ratio changed in vivo. 1C3 enhanced the efficacy of PD1/PD-L1 in MC38 tumor model. 1C3 is stable at 25 °C for 3 weeks (by SEC and CEX) and pl 9.0(by clEF).