Porous CuO/SnO2 nanofibers were prepared by co-dissolution and electrospinning, followed by annealing, and compounded with different amounts of carbon nanotubes (CNTs, 0-5 wt%). The performance of the composite based sensor was tested in different concentrations of H2S range from 0.1 to 0.5 ppm. The results showed that the gas sensor based CuO/SnO2 doped by CNTs (CNTs-CuO/SnO2) has a low optimum operating temperature, 40°C, good behavior in detecting low concentration H2S, short response and recovery time (8.3 and 11.5 s, respectively). And at the same time, compared with other gases, 3 wt% CNTs-CuO/SnO2 composite nanomaterial had excellent selectivity to H2S at low concentrations. The prepared gas sensor had great advantages in detecting low concentration H2S.