Double-diffusive staircase structure is investigated with CTD profile data in the Canadian Basin obtained from the third Chinese Arctic Expedition in summer of 2008.There exist extensive double-diffusive mixed phenomena in the Canadian Basin.Double-diffusive staircase is observed in the central Canada Basin and Mendeleyev Ridge.The distribution of double-diffusive staircase has significant spatial difference.There exists double-diffusive staircase through the depth range of 100~500 m.The 1 m to 5 m high staircase is located in the depth of thermocline.However,the staircase is not of uniform height in the deeper depth,with a wide depth range,which is called composite staircase.On the basis of double-diffusive flux laws, estimated vertical heat fluxes through the staircase are in the range 0.05~0.22 W/m2, indicating that the vertical transport of heat from the Atlantic Water in the central basin is unlikely to have a significant impact to the Canadian Basin ocean surface heat budget. However,the south on the Canada Basin and Chukchi Plateau where the well-formed staircase is absent possibly dominate the regionally averaged heat flux.