Cuprous oxide (Cu₂O) thin films were prepared by radio frequency(RF) magnetron sputtering,using a Cu₂O ceramics target in N_2and Ar mixture atmosphere.Effects of substrate te mperature and N_2flow rate on growth behaviour,crystalline structure,surface morphology and optical properti es of Cu₂O thin films are investigated.The results show that the thin films deposited with low N_2flow rate consist of CuO and Cu₂O phases.When the N_2flow rate increases to 12sccm,the thin films deposited at 300℃ are single phase Cu₂O.All thin films deposited under different N_2flow rates are characteristics of 3D growth.The root mean square (RMS) of surface roughness of thin films depends on N_2flow rates,the RMS of surfac e roughness increases with the increasing of N_2flow rates under low N_2flow rate,while decreases w ith the increasing of N_2flow rates under high N_2flow rate.Moreover,all thin films deposited under different N 2flow rates have a photoluminescence (PL) emission at ～475nm,corresponding to the optical band gap (E_g) ～(2.61±0.03) eV,the emission intensity of peak decreases with the increasing of N_2flow rates,and the peak positions show blue shifts with the increasing of N_2flow rates.