CdS/TiO2　composite　photocatalysts　were　made　by　the　method　of　secondary　ball　milling　at　different　ball　milling　speeds,　milling　time,　and　material　ratios.　After　the　secondary　ball　milling　process,　parts　of　the　samples　were　calcined　at　high　temperatures.　X-ray　diffraction　(XRD)　and　UV-Vis　diffuse　reflectance　spectroscopy　(DRS)　were　used　to　observe　the　powder　particle　size,　structural　defect,　bandgap,　and　absorption　spectrum　of　the　samples.　Combined　with　the　observation　results,　the　effects　of　ball　milling　speed,　time,　material　ratio,　and　high-temperature　calcination　on　the　photocatalytic　performance　of　CdS/TiO2　composite　samples　were　analyzed.　Furthermore,　the　methyl　orange　(MO)　was　chosen　to　simulate　pollutants,　and　the　photocatalytic　degradation　rate　of　CdS/TiO2　composite　photocatalysts　for　MO　was　evaluated　under　sunlight　and　UV　irradiation　conditions.　The　photocatalytic　degradation　efficiency　of　CdS/TiO2　photocatalyst　under　UV　irradiation　is　much　higher　than　that　under　sunlight　irradiation.　The　experimental　results　reveal　that　secondary　ball　milling　can　effectively　promote　the　formation　of　CdS/TiO2　composite　nanostructure　and　the　high-temperature　calcination　can　reduce　the　bandgap　width,　which　makes　the　samples　easier　to　be　excited.　When　the　ball　milling　speed,　time,　and　material　ratio　were　respectively　400　rpm,　10　h,　25:75,　and　then　calcined　at　high　temperature,　after　2　h　of　irradiation　under　UV　light,　CdS/TiO2　composite　photocatalysts　exhibited　maximum　photocatalytic　degradation　efficiency　of　57.84%.　©　2020　Mengya　Ye　et　al.,　published　by　De　Gruyter　2020.