The invention discloses a coaxial light-gathering secondary reflection groove type solar natural circulation heat-collecting device. A steam heat exchanger, a condensed water downcomer, a flow control valve, a condensation return pipe, a heat-collecting pipe, a steam ascending pipe, a steam heat exchanger and the like are sequentially connected to form a closed loop. The tail end of the steam ascending pipe is provided with a vacuum air suction hole, a light band sensor is arranged at the tail end of the heat-collecting pipe, the heat-collecting pipe is fixed on a system support through a heat-collecting pipe support, and the condensation return pipe is fixed on the system support through a condensation return pipe support. A secondary reflecting mirror is fixed on a secondary reflecting mirror frame, a main reflecting mirror is fixed on a main reflecting mirror frame, the secondary reflecting mirror frame is fixed on the main reflecting mirror frame through a secondary reflecting mirror support frame, and a rotating bearing is respectively connected with the system support and a hydraulic driving system. A secondary reflecting structure is introduced, the heat-collecting pipe and the rotating bearing are coaxially arranged, the problem of working medium leakage during rotating connection among pipeline ports is solved, and the long-term, safe and stable running of a system is guaranteed.