Abstract: Carbon-based material supported Cu is an efficient catalyst for methanol oxidative carbonylation to dimethyl carbonate, but Cu nanoparticles are prone to agglomeration and oxidation. Cu-BTC were prepared by hydrothermal method. And then CuO_x/C catalysts was prepared by pyrolysis Cu-BTC under N₂ atmosphere. The effect of pyrolysis temperature on Cu nanoparticle size, Cu valence state and performance for methanol oxidative carbonylation to dimethyl carbonate were investigated. The characterization results show that increasing the pyrolysis temperature is beneficial to the reduction of Cu²⁺ to (Cu⁰+Cu⁺), but would lead to the agglomeration of Cu nanoparticles. Catalytic activity decreases with the increasing of pyrolysis temperature. CuO_x/C-300, prepared by pyrolysis of Cu-BTC at 300℃, shows the optimized catalytic activity and the space-time yield of dimethyl carbonate is 1209 mg·g⁻¹·h⁻¹. This is attributed to the smallest particle size of Cu nanoparticles (7.5 nm). In addition, the space-time yield of dimethyl carbonate decreased to 468 mg·g⁻¹·h⁻¹ after 6 cycle experiments. The main reasons for catalyst inactivation are the oxidation of (Cu⁰+Cu⁺) and the agglomeration of Cu nanoparticles.