The invention discloses a solar energy storing and utilizing system and a method based on coal gasification. The solar energy storing and utilizing system comprises a heat collector, a gasifier, a carbon dioxide separating system, a combustion gas turbine power generating system and a compressor, wherein an outlet of the heat collector is communicated with a carbon dioxide inlet of the gasifier; an oxygen inlet, a steam inlet, a coal inlet and an ash residue outlet are formed in the gasifier; an outlet of the gasifier is communicated with an inlet of the carbon dioxide separating system; a coal outlet of the carbon dioxide separating system is communicated with an inlet of the combustion gas turbine power generating system; a carbon dioxide outlet of the carbon dioxide separating system is communicated with an inlet of the compressor; an outlet of the compressor is communicated with an inlet of the heat collector. According to the system and the method, coal gasification and chemical storage of solar energy can be organically combined.