CuS/MWCNTs counter electrode (CE) in high efficiency and stability is designed that CuS nanoparticles are grown on multi-wall carbon nanotubes (MWCNTs) in solutions to form CuS and MWCNTs composite in treelike structure that dispersed MWCNTs as branches support CuS nano-particles. The quantum dot sensitized solar cells (QDSCs) are assembled with CuS/MWCNT CE prepared with above composite, CdS and ZnS sensitized TiO2/RGO (reduced graphene oxide) photoanode and polysulfide electrolyte. The electrocatalytic activity of CEs can be analyzed through Nyquist curves and Tafel curves and typical photovoltaic parameters of QDSCs based on different CEs are obtained from J-V curves. CuS nanoparticles aggregate more severely with increase of CuS mass percentage according to TEM images and 100% CuS/MWCNTs CE within all samples exhibits the highest electrocatalytic activity and the power conversion efficiency (PCE) of QDSCs. Besides that, CuS/MWCNT CE exhibits the best photovoltaic stability. PCE of QDSCs with 100% CuS/MWCNTs CE decreases only 3%(from 5.254% to 5.086%) after 24 h illumination. Display omitted •CuS/MWCNTs composite in treelike structure is prepared in solutions with one-step method. CuS nanoparticles are grown on MWCNTs branches in tree-like structure.•100% CuS/MWCNTs counter electrode possesses high photovoltaic performance (Voc = 0.618 V, Jsc = 18.680 mA/cm2, FF = 0.455, η = 5.254 %). Its power conversion efficiency decreases only 3 %(from 5.254 % to 5.086 %) after 24 h illumination.